String.Split String.Split String.Split String.Split Method

Definition

Returns a string array that contains the substrings in this instance that are delimited by elements of a specified string or Unicode character array.

Overloads

Split(String[], Int32, StringSplitOptions) Split(String[], Int32, StringSplitOptions) Split(String[], Int32, StringSplitOptions) Split(String[], Int32, StringSplitOptions)

Splits a string into a maximum number of substrings based on the strings in an array. You can specify whether the substrings include empty array elements.

Split(String, Int32, StringSplitOptions) Split(String, Int32, StringSplitOptions) Split(String, Int32, StringSplitOptions)
Split(Char[], Int32, StringSplitOptions) Split(Char[], Int32, StringSplitOptions) Split(Char[], Int32, StringSplitOptions) Split(Char[], Int32, StringSplitOptions)

Splits a string into a maximum number of substrings based on the characters in an array.

Split(Char, Int32, StringSplitOptions) Split(Char, Int32, StringSplitOptions) Split(Char, Int32, StringSplitOptions)
Split(String[], StringSplitOptions) Split(String[], StringSplitOptions) Split(String[], StringSplitOptions) Split(String[], StringSplitOptions)

Splits a string into substrings based on the strings in an array. You can specify whether the substrings include empty array elements.

Split(Char[]) Split(Char[]) Split(Char[]) Split(Char[])

Splits a string into substrings that are based on the characters in an array.

Split(Char[], StringSplitOptions) Split(Char[], StringSplitOptions) Split(Char[], StringSplitOptions) Split(Char[], StringSplitOptions)

Splits a string into substrings based on the characters in an array. You can specify whether the substrings include empty array elements.

Split(Char[], Int32) Split(Char[], Int32) Split(Char[], Int32) Split(Char[], Int32)

Splits a string into a maximum number of substrings based on the characters in an array. You also specify the maximum number of substrings to return.

Split(Char, StringSplitOptions) Split(Char, StringSplitOptions) Split(Char, StringSplitOptions)
Split(String, StringSplitOptions) Split(String, StringSplitOptions) Split(String, StringSplitOptions)

Remarks

Split is used to break a delimited string into substrings. You can use either a character array to specify zero, one, or multiple delimiting characters (the Split(Char[]) method), or you can use a character array to specify zero, one, or multiple delimiting strings. Overloads of the Split method allow you to limit the number of substrings returned by the method (the Split(Char[], Int32) method), to determine whether empty strings are included in the returned substrings (the Split(Char[], StringSplitOptions) and Split(String[], StringSplitOptions) methods, or to do both (the Split(Char[], Int32, StringSplitOptions) and Split(String[], Int32, StringSplitOptions) methods).

Important

For more detailed information on the Split method, as well as for examples that call each overload, see the documentation for the individual overloads of Split.

The Split method is not always the best way to break a delimited string into substrings. If you don't want to extract all of the substrings of a delimited string, or if you want to parse a string based on a pattern instead of a set of delimiter characters, consider the following alternatives.

Regular expressions

If your strings conform to a fixed pattern, you can use a regular expression to extract and handle their elements. For example, if strings take the form "number operand number" you can use a regular expression to extract and handle the string's elements. Here's an example:

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      String[] expressions = { "16 + 21", "31 * 3", "28 / 3",
                               "42 - 18", "12 * 7",
                               "2, 4, 6, 8" };
      String pattern = @"(\d+)\s+([-+*/])\s+(\d+)";
      foreach (var expression in expressions)
         foreach (Match m in Regex.Matches(expression, pattern)) {
            int value1 = Int32.Parse(m.Groups[1].Value);
            int value2 = Int32.Parse(m.Groups[3].Value);
            switch (m.Groups[2].Value)
            {
               case "+":
                  Console.WriteLine("{0} = {1}", m.Value, value1 + value2);
                  break;
               case "-":
                  Console.WriteLine("{0} = {1}", m.Value, value1 - value2);
                  break;
               case "*":
                  Console.WriteLine("{0} = {1}", m.Value, value1 * value2);
                  break;
               case "/":
                  Console.WriteLine("{0} = {1:N2}", m.Value, value1 / value2);
                  break;
            }
         }
   }
}
// The example displays the following output:
//       16 + 21 = 37
//       31 * 3 = 93
//       28 / 3 = 9.33
//       42 - 18 = 24
//       12 * 7 = 84
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
      Dim expressions() As String = { "16 + 21", "31 * 3", "28 / 3",
                                      "42 - 18", "12 * 7",
                                      "2, 4, 6, 8" }

      Dim pattern As String = "(\d+)\s+([-+*/])\s+(\d+)"
      For Each expression In expressions
         For Each m As Match in Regex.Matches(expression, pattern)
            Dim value1 As Integer = Int32.Parse(m.Groups(1).Value)
            Dim value2 As Integer = Int32.Parse(m.Groups(3).Value)
            Select Case m.Groups(2).Value
               Case "+"
                  Console.WriteLine("{0} = {1}", m.Value, value1 + value2)
               Case "-"
                  Console.WriteLine("{0} = {1}", m.Value, value1 - value2)
               Case "*"
                  Console.WriteLine("{0} = {1}", m.Value, value1 * value2)
               Case "/"
                  Console.WriteLine("{0} = {1:N2}", m.Value, value1 / value2)
            End Select
         Next
      Next
   End Sub
End Module
' The example displays the following output:
'       16 + 21 = 37
'       31 * 3 = 93
'       28 / 3 = 9.33
'       42 - 18 = 24
'       12 * 7 = 84

The regular expression pattern (\d+)\s+([-+*/])\s+(\d+) is defined like this:

Pattern Description
(\d+) Match one or more decimal digits. This is the first capturing group.
\s+ Match one or more white-space characters.
([-+*/]) Match an arithmetic operator sign (+, -, *, or /). This is the second capturing group.
\s+ Match one or more white-space characters.
(\d+) Match one or more decimal digits. This is the third capturing group.

You can also use a regular expression to extract substrings from a string based on a pattern rather than a fixed set of characters. This is a common scenario when either of these conditions occurs:

  • One or more of the delimiter characters does not always serve as a delimiter in the String instance.

  • The sequence and number of delimiter characters is variable or unknown.

For example, the Split method cannot be used to split the following string, because the number of \n (in C#) or vbCrLf (in Visual Basic) characters is variable, and they don't always serve as delimiters.


[This is captured\ntext.]\n\n[\n[This is more captured text.]\n]  
\n[Some more captured text:\n   Option1\n   Option2][Terse text.]  

A regular expression can split this string easily, as the following example shows.

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      String input = "[This is captured\ntext.]\n\n[\n" +
                     "[This is more captured text.]\n]\n" +
                     "[Some more captured text:\n   Option1" +
                     "\n   Option2][Terse text.]";
      String pattern = @"\[([^\[\]]+)\]";
      int ctr = 0;
      foreach (Match m in Regex.Matches(input, pattern))
         Console.WriteLine("{0}: {1}", ++ctr, m.Groups[1].Value);
   }
}
// The example displays the following output:
//       1: This is captured
//       text.
//       2: This is more captured text.
//       3: Some more captured text:
//          Option1
//          Option2
//       4: Terse text.
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
      Dim input As String = String.Format("[This is captured{0}text.]" +
                                          "{0}{0}[{0}[This is more " +
                                          "captured text.]{0}{0}" +
                                          "[Some more captured text:" +
                                          "{0}   Option1" +
                                          "{0}   Option2][Terse text.]",
                                          vbCrLf)
      Dim pattern As String = "\[([^\[\]]+)\]"
      Dim ctr As Integer = 0
      For Each m As Match In Regex.Matches(input, pattern)
         ctr += 1
         Console.WriteLine("{0}: {1}", ctr, m.Groups(1).Value)
      Next
   End Sub
End Module
' The example displays the following output:
'       1: This is captured
'       text.
'       2: This is more captured text.
'       3: Some more captured text:
'          Option1
'          Option2
'       4: Terse text.

The regular expression pattern \[([^\[\]]+)\] is defined like this:

Pattern Description
\[ Match an opening bracket.
([^\[\]]+) Match any character that is not an opening or a closing bracket one or more times. This is the first capturing group.
\] Match a closing bracket.

The Regex.Split method is almost identical to String.Split, except that it splits a string based on a regular expression pattern instead of a fixed character set. For example, the following example uses the Regex.Split method to split a string that contains substrings delimited by various combinations of hyphens and other characters.

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      String input = "abacus -- alabaster - * - atrium -+- " +
                     "any -*- actual - + - armoir - - alarm";
      String pattern = @"\s-\s?[+*]?\s?-\s";
      String[] elements = Regex.Split(input, pattern);
      foreach (var element in elements)
         Console.WriteLine(element);
   }
}
// The example displays the following output:
//       abacus
//       alabaster
//       atrium
//       any
//       actual
//       armoir
//       alarm
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
      Dim input As String = "abacus -- alabaster - * - atrium -+- " +
                            "any -*- actual - + - armoir - - alarm"
      Dim pattern As String = "\s-\s?[+*]?\s?-\s"
      Dim elements() As String = Regex.Split(input, pattern)
      For Each element In elements
         Console.WriteLine(element)
      Next
   End Sub
End Module
' The example displays the following output:
'       abacus
'       alabaster
'       atrium
'       any
'       actual
'       armoir
'       alarm

The regular expression pattern \s-\s?[+*]?\s?-\s is defined like this:

Pattern Description
\s- Match a white-space character followed by a hyphen.
\s? Match zero or one white-space character.
[+*]? Match zero or one occurrence of either the + or * character.
\s? Match zero or one white-space character.
-\s Match a hyphen followed by a white-space character.

Search methods and the Substring method

If you aren't interested in all of the substrings in a string, you might prefer to work with one of the string comparison methods that returns the index at which the match begins. You can then call the Substring method to extract the substring that you want. The string comparison methods include:

  • IndexOf, which returns the zero-based index of the first occurrence of a character or string in a string instance.

  • IndexOfAny, which returns the zero-based index in the current string instance of the first occurrence of any character in a character array.

  • LastIndexOf, which returns the zero-based index of the last occurrence of a character or string in a string instance.

  • LastIndexOfAny, which returns a zero-based index in the current string instance of the last occurrence of any character in a character array.

The following example uses the IndexOf method to find the periods in a string. It then uses the Substring method to return full sentences.

using System;
using System.Collections.Generic;

public class Example
{
   public static void Main()
   {
      String value = "This is the first sentence in a string. " +
                     "More sentences will follow. For example, " +
                     "this is the third sentence. This is the " +
                     "fourth. And this is the fifth and final " +
                     "sentence.";
      var sentences = new List<String>();
      int position = 0;
      int start = 0;
      // Extract sentences from the string.
      do {
         position = value.IndexOf('.', start);
         if (position >= 0) {
            sentences.Add(value.Substring(start, position - start + 1).Trim());
            start = position + 1;
         }
      } while (position > 0);

      // Display the sentences.
      foreach (var sentence in sentences)
         Console.WriteLine(sentence);
   }
}
// The example displays the following output:
//       This is the first sentence in a string.
//       More sentences will follow.
//       For example, this is the third sentence.
//       This is the fourth.
//       And this is the fifth and final sentence.
Imports System.Collections.Generic

Module Example
   Public Sub Main()
      Dim value As String = "This is the first sentence in a string. " +
                            "More sentences will follow. For example, " +
                            "this is the third sentence. This is the " +
                            "fourth. And this is the fifth and final " +
                            "sentence."
      Dim sentences As New List(Of String)
      Dim position As Integer = 0
      Dim start As Integer = 0
      ' Extract sentences from the string.
      Do
         position = value.IndexOf("."c, start)
         If position >= 0 Then
            sentences.Add(value.Substring(start, position - start + 1).Trim())
            start = position + 1
         End If
      Loop While position > 0
      
      ' Display the sentences.
      For Each sentence In sentences
         Console.WriteLine(sentence)
      Next
   End Sub
End Module
' The example displays the following output:
'       This is the first sentence in a string.
'       More sentences will follow.
'       For example, this is the third sentence.
'       This is the fourth.
'       And this is the fifth and final sentence.

Split(String[], Int32, StringSplitOptions) Split(String[], Int32, StringSplitOptions) Split(String[], Int32, StringSplitOptions) Split(String[], Int32, StringSplitOptions)

Splits a string into a maximum number of substrings based on the strings in an array. You can specify whether the substrings include empty array elements.

public:
 cli::array <System::String ^> ^ Split(cli::array <System::String ^> ^ separator, int count, StringSplitOptions options);
[System.Runtime.InteropServices.ComVisible(false)]
public string[] Split (string[] separator, int count, StringSplitOptions options);
member this.Split : string[] * int * StringSplitOptions -> string[]
Public Function Split (separator As String(), count As Integer, options As StringSplitOptions) As String()

Parameters

separator
String[]

A string array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

count
Int32 Int32 Int32 Int32

The maximum number of substrings to return.

options
StringSplitOptions StringSplitOptions StringSplitOptions StringSplitOptions

RemoveEmptyEntries to omit empty array elements from the array returned; or None to include empty array elements in the array returned.

Returns

String[]

An array whose elements contain the substrings in this string that are delimited by one or more strings in separator. For more information, see the Remarks section.

Exceptions

Examples

The following example uses the StringSplitOptions enumeration to include or exclude substrings generated by the Split method.

// This example demonstrates the String.Split(Char[], Boolean) and 
//                               String.Split(Char[], Int32, Boolean) methods
using namespace System;
void Show( array<String^>^entries )
{
   Console::WriteLine( "The return value contains these {0} elements:", entries->Length );
   System::Collections::IEnumerator^ myEnum = entries->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ entry = safe_cast<String^>(myEnum->Current);
      Console::Write( "<{0}>", entry );
   }

   Console::Write( "{0}{0}", Environment::NewLine );
}

int main()
{
   String^ s = ",one,,,two,,,,,three,,";
   array<Char>^sep = gcnew array<Char>{
      ','
   };
   array<String^>^result;
   
   //
   Console::WriteLine( "The original string is \"{0}\".", s );
   Console::WriteLine( "The separation character is '{0}'.", sep[ 0 ] );
   Console::WriteLine();
   
   //
   Console::WriteLine( "Split the string and return all elements:" );
   result = s->Split( sep, StringSplitOptions::None );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return all non-empty elements:" );
   result = s->Split( sep, StringSplitOptions::RemoveEmptyEntries );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return 2 elements:" );
   result = s->Split( sep, 2, StringSplitOptions::None );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return 2 non-empty elements:" );
   result = s->Split( sep, 2, StringSplitOptions::RemoveEmptyEntries );
   Show( result );
}

/*
This example produces the following results:

The original string is ",one,,,two,,,,,three,,".
The separation character is ','.

Split the string and return all elements:
The return value contains these 12 elements:
<><one><><><two><><><><><three><><>

Split the string and return all non-empty elements:
The return value contains these 3 elements:
<one><two><three>

Split the string and return 2 elements:
The return value contains these 2 elements:
<><one,,,two,,,,,three,,>

Split the string and return 2 non-empty elements:
The return value contains these 2 elements:
<one><,,two,,,,,three,,>

*/
// This example demonstrates the String() methods that use
// the StringSplitOptions enumeration.
using System;

class Sample 
{
    public static void Main() 
    {
    string s1 = ",ONE,,TWO,,,THREE,,";
    string s2 = "[stop]" +
                "ONE[stop][stop]" +
                "TWO[stop][stop][stop]" +
                "THREE[stop][stop]";
    char[] charSeparators = new char[] {','};
    string[] stringSeparators = new string[] {"[stop]"};
    string[] result;
// ------------------------------------------------------------------------------
// Split a string delimited by characters.
// ------------------------------------------------------------------------------
    Console.WriteLine("1) Split a string delimited by characters:\n");

// Display the original string and delimiter characters.
    Console.WriteLine("1a )The original string is \"{0}\".", s1);
    Console.WriteLine("The delimiter character is '{0}'.\n", 
                       charSeparators[0]);

// Split a string delimited by characters and return all elements.
    Console.WriteLine("1b) Split a string delimited by characters and " +
                      "return all elements:");
    result = s1.Split(charSeparators, StringSplitOptions.None);
    Show(result);

// Split a string delimited by characters and return all non-empty elements.
    Console.WriteLine("1c) Split a string delimited by characters and " +
                      "return all non-empty elements:");
    result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the string and empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("1d) Split a string delimited by characters and " +
                      "return 2 elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("1e) Split a string delimited by characters and " +
                      "return 2 non-empty elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// ------------------------------------------------------------------------------
// Split a string delimited by another string.
// ------------------------------------------------------------------------------
    Console.WriteLine("2) Split a string delimited by another string:\n");

// Display the original string and delimiter string.
    Console.WriteLine("2a) The original string is \"{0}\".", s2);
    Console.WriteLine("The delimiter string is \"{0}\".\n", stringSeparators[0]);

// Split a string delimited by another string and return all elements.
    Console.WriteLine("2b) Split a string delimited by another string and " +
                      "return all elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.None);
    Show(result);

// Split the original string at the delimiter and return all non-empty elements.
    Console.WriteLine("2c) Split a string delimited by another string and " +
                      "return all non-empty elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("2d) Split a string delimited by another string and " +
                      "return 2 elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("2e) Split a string delimited by another string and " + 
                      "return 2 non-empty elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);
    }

// Display the array of separated strings.
    public static void Show(string[] entries)
    {
    Console.WriteLine("The return value contains these {0} elements:", entries.Length);
    foreach (string entry in entries)
        {
        Console.Write("<{0}>", entry);
        }
    Console.Write("\n\n");
    }
}
/*
This example produces the following results:

1) Split a string delimited by characters:

1a )The original string is ",ONE,,TWO,,,THREE,,".
The delimiter character is ','.

1b) Split a string delimited by characters and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

1c) Split a string delimited by characters and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

1d) Split a string delimited by characters and return 2 elements:
The return value contains these 2 elements:
<><ONE,,TWO,,,THREE,,>

1e) Split a string delimited by characters and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO,,,THREE,,>

2) Split a string delimited by another string:

2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
The delimiter string is "[stop]".

2b) Split a string delimited by another string and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

2c) Split a string delimited by another string and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

2d) Split a string delimited by another string and return 2 elements:
The return value contains these 2 elements:
<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>

2e) Split a string delimited by another string and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO[stop][stop][stop]THREE[stop][stop]>

*/

' This example demonstrates the String() methods that use
' the StringSplitOptions enumeration.
Imports System

Class Sample
    Public Shared Sub Main() 
        Dim s1 As String = ",ONE,,TWO,,,THREE,,"
        Dim s2 As String = "[stop]" & _
                           "ONE[stop][stop]" & _
                           "TWO[stop][stop][stop]" & _
                           "THREE[stop][stop]"
        Dim charSeparators() As Char = {","c}
        Dim stringSeparators() As String = {"[stop]"}
        Dim result() As String
        ' ------------------------------------------------------------------------------
        ' Split a string delimited by characters.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("1) Split a string delimited by characters:" & vbCrLf)
        
        ' Display the original string and delimiter characters.
        Console.WriteLine("1a )The original string is ""{0}"".", s1)
        Console.WriteLine("The delimiter character is '{0}'." & vbCrLf, charSeparators(0))
        
        ' Split a string delimited by characters and return all elements.
        Console.WriteLine("1b) Split a string delimited by characters and " & _
                          "return all elements:")
        result = s1.Split(charSeparators, StringSplitOptions.None)
        Show(result)
        
        ' Split a string delimited by characters and return all non-empty elements.
        Console.WriteLine("1c) Split a string delimited by characters and " & _
                          "return all non-empty elements:")
        result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' Split the original string into the string and empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("1d) Split a string delimited by characters and " & _
                          "return 2 elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("1e) Split a string delimited by characters and " & _
                          "return 2 non-empty elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' ------------------------------------------------------------------------------
        ' Split a string delimited by another string.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("2) Split a string delimited by another string:" & vbCrLf)
        
        ' Display the original string and delimiter string.
        Console.WriteLine("2a) The original string is ""{0}"".", s2)
        Console.WriteLine("The delimiter string is ""{0}""." & vbCrLf, stringSeparators(0))
        
        ' Split a string delimited by another string and return all elements.
        Console.WriteLine("2b) Split a string delimited by another string and " & _
                          "return all elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string at the delimiter and return all non-empty elements.
        Console.WriteLine("2c) Split a string delimited by another string and " & _
                          "return all non-empty elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' Split the original string into the empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("2d) Split a string delimited by another string and " & _
                          "return 2 elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("2e) Split a string delimited by another string and " & _
                          "return 2 non-empty elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
    
    End Sub 'Main
    
    
    ' Display the array of separated strings.
    Public Shared Sub Show(ByVal entries() As String) 
        Console.WriteLine("The return value contains these {0} elements:", entries.Length)
        Dim entry As String
        For Each entry In  entries
            Console.Write("<{0}>", entry)
        Next entry
        Console.Write(vbCrLf & vbCrLf)
    
    End Sub 'Show
End Class 'Sample
'
'This example produces the following results:
'
'1) Split a string delimited by characters:
'
'1a )The original string is ",ONE,,TWO,,,THREE,,".
'The delimiter character is ','.
'
'1b) Split a string delimited by characters and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'1c) Split a string delimited by characters and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'1d) Split a string delimited by characters and return 2 elements:
'The return value contains these 2 elements:
'<><ONE,,TWO,,,THREE,,>
'
'1e) Split a string delimited by characters and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO,,,THREE,,>
'
'2) Split a string delimited by another string:
'
'2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
'The delimiter string is "[stop]".
'
'2b) Split a string delimited by another string and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'2c) Split a string delimited by another string and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'2d) Split a string delimited by another string and return 2 elements:
'The return value contains these 2 elements:
'<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>
'
'2e) Split a string delimited by another string and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO[stop][stop][stop]THREE[stop][stop]>
'

Remarks

Return value details

Delimiter strings are not included in the elements of the returned array.

If this instance does not contain any of the strings in separator, or the count parameter is 1, the returned array consists of a single element that contains this instance. If the separator parameter is null or contains no characters, white-space characters are assumed to be the delimiters. White-space characters are defined by the Unicode standard and return true if they are passed to the Char.IsWhiteSpace method. However, if the separator parameter in the call to this method overload is null, compiler overload resolution fails. To unambiguously identify the called method, your code must indicate the type of the null. The following example shows several ways to unambiguously identify this overload.

string phrase = "The quick  brown fox";
string[] words;

words = phrase.Split(default(string[]), 3, StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split((string[]) null, 3, StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split(null as string[], 3, StringSplitOptions.RemoveEmptyEntries);
Dim phrase As String = "The quick brown fox"
Dim words() As String

words = phrase.Split(TryCast(Nothing, String()), 3, 
                       StringSplitOptions.RemoveEmptyEntries)

words = phrase.Split(New String() {}, 3,
                     StringSplitOptions.RemoveEmptyEntries)

If the count parameter is zero, or the options parameter is RemoveEmptyEntries and the length of this instance is zero, an empty array is returned.

Each element of separator defines a separate delimiter that consists of one or more characters. If the options parameter is None, and two delimiters are adjacent or a delimiter is found at the beginning or end of this instance, the corresponding array element contains Empty.

If there are more than count substrings in this instance, the first count minus 1 substrings are returned in the first count minus 1 elements of the return value, and the remaining characters in this instance are returned in the last element of the return value.

If count is greater than the number of substrings, the available substrings are returned and no exception is thrown.

The separator array

If any of the elements in separator consists of multiple characters, the entire substring is considered a delimiter. For example, if one of the elements in separator is "10", attempting to split the string "This10is10a10string." returns this four-element array: { "This", "is", "a", "string." }.

Comparison details

The Split method extracts the substrings in this string that are delimited by one or more of the strings in the separator parameter, and returns those substrings as elements of an array.

The Split method looks for delimiters by performing comparisons using case-sensitive ordinal sort rules. For more information about word, string, and ordinal sorts, see the System.Globalization.CompareOptions enumeration.

The Split method ignores any element of separator whose value is null or the empty string ("").

To avoid ambiguous results when strings in separator have characters in common, the Split method proceeds from the beginning to the end of the value of the instance, and matches the first element in separator that is equal to a delimiter in the instance. The order in which substrings are encountered in the instance takes precedence over the order of elements in separator.

For example, consider an instance whose value is "abcdef". If the first element in separator was "ef" and the second element was "bcde", the result of the split operation would be "a" and "f". This is because the substring in the instance, "bcde", is encountered and matches an element in separator before the substring "f" is encountered.

However, if the first element of separator was "bcd" and the second element was "bc", the result of the split operation would be "a" and "ef". This is because "bcd" is the first delimiter in separator that matches a delimiter in the instance. If the order of the separators was reversed so the first element was "bc" and the second element was "bcd", the result would be "a" and "def".

Performance considerations

The Split methods allocate memory for the returned array object and a String object for each array element. If your application requires optimal performance or if managing memory allocation is critical in your application, consider using the IndexOf or IndexOfAny method, and optionally the Compare method, to locate a substring within a string.

If you are splitting a string at a separator character, use the IndexOf or IndexOfAny method to locate a separator character in the string. If you are splitting a string at a separator string, use the IndexOf or IndexOfAny method to locate the first character of the separator string. Then use the Compare method to determine whether the characters after that first character are equal to the remaining characters of the separator string.

In addition, if the same set of characters is used to split strings in multiple Split method calls, consider creating a single array and referencing it in each method call. This significantly reduces the additional overhead of each method call.

Notes to Callers

In the .NET Framework 3.5 and earlier versions, if the Split(Char[]) method is passed a separator that is null or contains no characters, the method uses a slightly different set of characters to split the string than the Trim(Char[]) method does to trim the string. In the .NET Framework 4, both methods use an identical set of Unicode white-space characters.

Split(String, Int32, StringSplitOptions) Split(String, Int32, StringSplitOptions) Split(String, Int32, StringSplitOptions)

public string[] Split (string separator, int count, StringSplitOptions options = System.StringSplitOptions.None);
member this.Split : string * int * StringSplitOptions -> string[]
Public Function Split (separator As String, count As Integer, Optional options As StringSplitOptions = System.StringSplitOptions.None) As String()

Parameters

Returns

String[]

Split(Char[], Int32, StringSplitOptions) Split(Char[], Int32, StringSplitOptions) Split(Char[], Int32, StringSplitOptions) Split(Char[], Int32, StringSplitOptions)

Splits a string into a maximum number of substrings based on the characters in an array.

public:
 cli::array <System::String ^> ^ Split(cli::array <char> ^ separator, int count, StringSplitOptions options);
[System.Runtime.InteropServices.ComVisible(false)]
public string[] Split (char[] separator, int count, StringSplitOptions options);
member this.Split : char[] * int * StringSplitOptions -> string[]
Public Function Split (separator As Char(), count As Integer, options As StringSplitOptions) As String()

Parameters

separator
Char[]

A character array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

count
Int32 Int32 Int32 Int32

The maximum number of substrings to return.

options
StringSplitOptions StringSplitOptions StringSplitOptions StringSplitOptions

RemoveEmptyEntries to omit empty array elements from the array returned; or None to include empty array elements in the array returned.

Returns

String[]

An array whose elements contain the substrings in this string that are delimited by one or more characters in separator. For more information, see the Remarks section.

Exceptions

Examples

The following example uses the StringSplitOptions enumeration to include or exclude substrings generated by the Split method.

// This example demonstrates the String.Split(Char[], Boolean) and 
//                               String.Split(Char[], Int32, Boolean) methods
using namespace System;
void Show( array<String^>^entries )
{
   Console::WriteLine( "The return value contains these {0} elements:", entries->Length );
   System::Collections::IEnumerator^ myEnum = entries->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ entry = safe_cast<String^>(myEnum->Current);
      Console::Write( "<{0}>", entry );
   }

   Console::Write( "{0}{0}", Environment::NewLine );
}

int main()
{
   String^ s = ",one,,,two,,,,,three,,";
   array<Char>^sep = gcnew array<Char>{
      ','
   };
   array<String^>^result;
   
   //
   Console::WriteLine( "The original string is \"{0}\".", s );
   Console::WriteLine( "The separation character is '{0}'.", sep[ 0 ] );
   Console::WriteLine();
   
   //
   Console::WriteLine( "Split the string and return all elements:" );
   result = s->Split( sep, StringSplitOptions::None );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return all non-empty elements:" );
   result = s->Split( sep, StringSplitOptions::RemoveEmptyEntries );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return 2 elements:" );
   result = s->Split( sep, 2, StringSplitOptions::None );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return 2 non-empty elements:" );
   result = s->Split( sep, 2, StringSplitOptions::RemoveEmptyEntries );
   Show( result );
}

/*
This example produces the following results:

The original string is ",one,,,two,,,,,three,,".
The separation character is ','.

Split the string and return all elements:
The return value contains these 12 elements:
<><one><><><two><><><><><three><><>

Split the string and return all non-empty elements:
The return value contains these 3 elements:
<one><two><three>

Split the string and return 2 elements:
The return value contains these 2 elements:
<><one,,,two,,,,,three,,>

Split the string and return 2 non-empty elements:
The return value contains these 2 elements:
<one><,,two,,,,,three,,>

*/
// This example demonstrates the String() methods that use
// the StringSplitOptions enumeration.
using System;

class Sample 
{
    public static void Main() 
    {
    string s1 = ",ONE,,TWO,,,THREE,,";
    string s2 = "[stop]" +
                "ONE[stop][stop]" +
                "TWO[stop][stop][stop]" +
                "THREE[stop][stop]";
    char[] charSeparators = new char[] {','};
    string[] stringSeparators = new string[] {"[stop]"};
    string[] result;
// ------------------------------------------------------------------------------
// Split a string delimited by characters.
// ------------------------------------------------------------------------------
    Console.WriteLine("1) Split a string delimited by characters:\n");

// Display the original string and delimiter characters.
    Console.WriteLine("1a )The original string is \"{0}\".", s1);
    Console.WriteLine("The delimiter character is '{0}'.\n", 
                       charSeparators[0]);

// Split a string delimited by characters and return all elements.
    Console.WriteLine("1b) Split a string delimited by characters and " +
                      "return all elements:");
    result = s1.Split(charSeparators, StringSplitOptions.None);
    Show(result);

// Split a string delimited by characters and return all non-empty elements.
    Console.WriteLine("1c) Split a string delimited by characters and " +
                      "return all non-empty elements:");
    result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the string and empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("1d) Split a string delimited by characters and " +
                      "return 2 elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("1e) Split a string delimited by characters and " +
                      "return 2 non-empty elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// ------------------------------------------------------------------------------
// Split a string delimited by another string.
// ------------------------------------------------------------------------------
    Console.WriteLine("2) Split a string delimited by another string:\n");

// Display the original string and delimiter string.
    Console.WriteLine("2a) The original string is \"{0}\".", s2);
    Console.WriteLine("The delimiter string is \"{0}\".\n", stringSeparators[0]);

// Split a string delimited by another string and return all elements.
    Console.WriteLine("2b) Split a string delimited by another string and " +
                      "return all elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.None);
    Show(result);

// Split the original string at the delimiter and return all non-empty elements.
    Console.WriteLine("2c) Split a string delimited by another string and " +
                      "return all non-empty elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("2d) Split a string delimited by another string and " +
                      "return 2 elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("2e) Split a string delimited by another string and " + 
                      "return 2 non-empty elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);
    }

// Display the array of separated strings.
    public static void Show(string[] entries)
    {
    Console.WriteLine("The return value contains these {0} elements:", entries.Length);
    foreach (string entry in entries)
        {
        Console.Write("<{0}>", entry);
        }
    Console.Write("\n\n");
    }
}
/*
This example produces the following results:

1) Split a string delimited by characters:

1a )The original string is ",ONE,,TWO,,,THREE,,".
The delimiter character is ','.

1b) Split a string delimited by characters and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

1c) Split a string delimited by characters and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

1d) Split a string delimited by characters and return 2 elements:
The return value contains these 2 elements:
<><ONE,,TWO,,,THREE,,>

1e) Split a string delimited by characters and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO,,,THREE,,>

2) Split a string delimited by another string:

2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
The delimiter string is "[stop]".

2b) Split a string delimited by another string and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

2c) Split a string delimited by another string and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

2d) Split a string delimited by another string and return 2 elements:
The return value contains these 2 elements:
<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>

2e) Split a string delimited by another string and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO[stop][stop][stop]THREE[stop][stop]>

*/

' This example demonstrates the String() methods that use
' the StringSplitOptions enumeration.
Imports System

Class Sample
    Public Shared Sub Main() 
        Dim s1 As String = ",ONE,,TWO,,,THREE,,"
        Dim s2 As String = "[stop]" & _
                           "ONE[stop][stop]" & _
                           "TWO[stop][stop][stop]" & _
                           "THREE[stop][stop]"
        Dim charSeparators() As Char = {","c}
        Dim stringSeparators() As String = {"[stop]"}
        Dim result() As String
        ' ------------------------------------------------------------------------------
        ' Split a string delimited by characters.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("1) Split a string delimited by characters:" & vbCrLf)
        
        ' Display the original string and delimiter characters.
        Console.WriteLine("1a )The original string is ""{0}"".", s1)
        Console.WriteLine("The delimiter character is '{0}'." & vbCrLf, charSeparators(0))
        
        ' Split a string delimited by characters and return all elements.
        Console.WriteLine("1b) Split a string delimited by characters and " & _
                          "return all elements:")
        result = s1.Split(charSeparators, StringSplitOptions.None)
        Show(result)
        
        ' Split a string delimited by characters and return all non-empty elements.
        Console.WriteLine("1c) Split a string delimited by characters and " & _
                          "return all non-empty elements:")
        result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' Split the original string into the string and empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("1d) Split a string delimited by characters and " & _
                          "return 2 elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("1e) Split a string delimited by characters and " & _
                          "return 2 non-empty elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' ------------------------------------------------------------------------------
        ' Split a string delimited by another string.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("2) Split a string delimited by another string:" & vbCrLf)
        
        ' Display the original string and delimiter string.
        Console.WriteLine("2a) The original string is ""{0}"".", s2)
        Console.WriteLine("The delimiter string is ""{0}""." & vbCrLf, stringSeparators(0))
        
        ' Split a string delimited by another string and return all elements.
        Console.WriteLine("2b) Split a string delimited by another string and " & _
                          "return all elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string at the delimiter and return all non-empty elements.
        Console.WriteLine("2c) Split a string delimited by another string and " & _
                          "return all non-empty elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' Split the original string into the empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("2d) Split a string delimited by another string and " & _
                          "return 2 elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("2e) Split a string delimited by another string and " & _
                          "return 2 non-empty elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
    
    End Sub 'Main
    
    
    ' Display the array of separated strings.
    Public Shared Sub Show(ByVal entries() As String) 
        Console.WriteLine("The return value contains these {0} elements:", entries.Length)
        Dim entry As String
        For Each entry In  entries
            Console.Write("<{0}>", entry)
        Next entry
        Console.Write(vbCrLf & vbCrLf)
    
    End Sub 'Show
End Class 'Sample
'
'This example produces the following results:
'
'1) Split a string delimited by characters:
'
'1a )The original string is ",ONE,,TWO,,,THREE,,".
'The delimiter character is ','.
'
'1b) Split a string delimited by characters and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'1c) Split a string delimited by characters and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'1d) Split a string delimited by characters and return 2 elements:
'The return value contains these 2 elements:
'<><ONE,,TWO,,,THREE,,>
'
'1e) Split a string delimited by characters and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO,,,THREE,,>
'
'2) Split a string delimited by another string:
'
'2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
'The delimiter string is "[stop]".
'
'2b) Split a string delimited by another string and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'2c) Split a string delimited by another string and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'2d) Split a string delimited by another string and return 2 elements:
'The return value contains these 2 elements:
'<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>
'
'2e) Split a string delimited by another string and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO[stop][stop][stop]THREE[stop][stop]>
'

Remarks

Delimiter characters are not included in the elements of the returned array.

If this instance does not contain any of the characters in separator, or the count parameter is 1, the returned array consists of a single element that contains this instance. If the separator parameter is null or contains no characters, white-space characters are assumed to be the delimiters. White-space characters are defined by the Unicode standard and return true if they are passed to the Char.IsWhiteSpace method. However, if the separator parameter in the call to this method overload is null, compiler overload resolution fails. To unambiguously identify the called method, your code must indicate the type of the null. The following example shows several ways to unambiguously identify this overload.

string phrase = "The quick  brown fox";
string[] words;

words = phrase.Split(default(Char[]), 3, StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split((char[]) null, 3, StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split(null as char[], 3, StringSplitOptions.RemoveEmptyEntries);
Dim phrase As String = "The quick brown fox"
Dim words() As String

words = phrase.Split(TryCast(Nothing, Char()), 3, 
                       StringSplitOptions.RemoveEmptyEntries)

words = phrase.Split(New Char() {}, 3,
                     StringSplitOptions.RemoveEmptyEntries)

If the count parameter is zero, or the options parameter is RemoveEmptyEntries and the length of this instance is zero, an empty array is returned.

Each element of separator defines a separate delimiter character. If the options parameter is None, and two delimiters are adjacent or a delimiter is found at the beginning or end of this instance, the corresponding array element contains Empty.

If there are more than count substrings in this instance, the first count minus 1 substrings are returned in the first count minus 1 elements of the return value, and the remaining characters in this instance are returned in the last element of the return value.

If count is greater than the number of substrings, the available substrings are returned and no exception is thrown.

Performance Considerations

The Split methods allocate memory for the returned array object and a String object for each array element. If your application requires optimal performance or if managing memory allocation is critical in your application, consider using the IndexOf or IndexOfAny method, and optionally the Compare method, to locate a substring within a string.

If you are splitting a string at a separator character, use the IndexOf or IndexOfAny method to locate a separator character in the string. If you are splitting a string at a separator string, use the IndexOf or IndexOfAny method to locate the first character of the separator string. Then use the Compare method to determine whether the characters after that first character are equal to the remaining characters of the separator string.

In addition, if the same set of characters is used to split strings in multiple Split method calls, consider creating a single array and referencing it in each method call. This significantly reduces the additional overhead of each method call.

Notes to Callers

In the .NET Framework 3.5 and earlier versions, if the Split(Char[]) method is passed a separator that is null or contains no characters, the method uses a slightly different set of characters to split the string than the Trim(Char[]) method does to trim the string. In the .NET Framework 4, both methods use an identical set of Unicode white-space characters.

Split(Char, Int32, StringSplitOptions) Split(Char, Int32, StringSplitOptions) Split(Char, Int32, StringSplitOptions)

public string[] Split (char separator, int count, StringSplitOptions options = System.StringSplitOptions.None);
member this.Split : char * int * StringSplitOptions -> string[]
Public Function Split (separator As Char, count As Integer, Optional options As StringSplitOptions = System.StringSplitOptions.None) As String()

Parameters

separator
Char Char Char Char

Returns

String[]

Split(String[], StringSplitOptions) Split(String[], StringSplitOptions) Split(String[], StringSplitOptions) Split(String[], StringSplitOptions)

Splits a string into substrings based on the strings in an array. You can specify whether the substrings include empty array elements.

public:
 cli::array <System::String ^> ^ Split(cli::array <System::String ^> ^ separator, StringSplitOptions options);
[System.Runtime.InteropServices.ComVisible(false)]
public string[] Split (string[] separator, StringSplitOptions options);
member this.Split : string[] * StringSplitOptions -> string[]
Public Function Split (separator As String(), options As StringSplitOptions) As String()

Parameters

separator
String[]

A string array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

options
StringSplitOptions StringSplitOptions StringSplitOptions StringSplitOptions

RemoveEmptyEntries to omit empty array elements from the array returned; or None to include empty array elements in the array returned.

Returns

String[]

An array whose elements contain the substrings in this string that are delimited by one or more strings in separator. For more information, see the Remarks section.

Exceptions

Examples

The following example illustrates the difference in the arrays returned by calling a string's String.Split(String[], StringSplitOptions) method with its options parameter equal to StringSplitOptions.None and StringSplitOptions.RemoveEmptyEntries.

using System;

class Example 
{
   public static void Main() 
   {
      string source = "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]";
      string[] stringSeparators = new string[] {"[stop]"};
      string[] result;
      
      // Display the original string and delimiter string.
      Console.WriteLine("Splitting the string:\n   \"{0}\".", source);
      Console.WriteLine();
      Console.WriteLine("Using the delimiter string:\n   \"{0}\"", 
                        stringSeparators[0]);
      Console.WriteLine();                           
         
      // Split a string delimited by another string and return all elements.
      result = source.Split(stringSeparators, StringSplitOptions.None);
      Console.WriteLine("Result including all elements ({0} elements):", 
                        result.Length);
      Console.Write("   ");
      foreach (string s in result)
      {
         Console.Write("'{0}' ", String.IsNullOrEmpty(s) ? "<>" : s);                   
      }
      Console.WriteLine();
      Console.WriteLine();

      // Split delimited by another string and return all non-empty elements.
      result = source.Split(stringSeparators, 
                            StringSplitOptions.RemoveEmptyEntries);
      Console.WriteLine("Result including non-empty elements ({0} elements):", 
                        result.Length);
      Console.Write("   ");
      foreach (string s in result)
      {
         Console.Write("'{0}' ", String.IsNullOrEmpty(s) ? "<>" : s);                   
      }
      Console.WriteLine();
   }
}
// The example displays the following output:
//    Splitting the string:
//       "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
//    
//    Using the delimiter string:
//       "[stop]"
//    
//    Result including all elements (9 elements):
//       '<>' 'ONE' '<>' 'TWO' '<>' '<>' 'THREE' '<>' '<>'
//    
//    Result including non-empty elements (3 elements):
//       'ONE' 'TWO' 'THREE'
Module Example
   Public Sub Main()
      Dim source As String = "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]"
      Dim stringSeparators() As String = {"[stop]"}
      Dim result() As String
      
      ' Display the original string and delimiter string.
      Console.WriteLine("Splitting the string:{0}   '{1}'.", vbCrLf, source)
      Console.WriteLine()
      Console.WriteLine("Using the delimiter string:{0}   '{1}'.", _
                        vbCrLf, stringSeparators(0))
      Console.WriteLine()                          
         
      ' Split a string delimited by another string and return all elements.
      result = source.Split(stringSeparators, StringSplitOptions.None)
      Console.WriteLine("Result including all elements ({0} elements):", _ 
                        result.Length)
      Console.Write("   ")
      For Each s As String In result
         Console.Write("'{0}' ", IIf(String.IsNullOrEmpty(s), "<>", s))                   
      Next
      Console.WriteLine()
      Console.WriteLine()

      ' Split delimited by another string and return all non-empty elements.
      result = source.Split(stringSeparators, _ 
                            StringSplitOptions.RemoveEmptyEntries)
      Console.WriteLine("Result including non-empty elements ({0} elements):", _ 
                        result.Length)
      Console.Write("   ")
      For Each s As String In result
         Console.Write("'{0}' ", IIf(String.IsNullOrEmpty(s), "<>", s))                   
      Next
      Console.WriteLine()
   End Sub
End Module
' The example displays the following output:
'    Splitting the string:
'       "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
'    
'    Using the delimiter string:
'       "[stop]"
'    
'    Result including all elements (9 elements):
'       '<>' 'ONE' '<>' 'TWO' '<>' '<>' 'THREE' '<>' '<>'
'    
'    Result including non-empty elements (3 elements):
'       'ONE' 'TWO' 'THREE'

The following example defines an array of separators that include punctuation and white-space characters. Passing this array along with a value of StringSplitOptions.RemoveEmptyEntries to the Split(String[], StringSplitOptions) method returns an array that consists of the individual words from the string.

using System;

public class Example
{
   public static void Main()
   {
      string[] separators = {",", ".", "!", "?", ";", ":", " "};
      string value = "The handsome, energetic, young dog was playing with his smaller, more lethargic litter mate.";
      string[] words = value.Split(separators, StringSplitOptions.RemoveEmptyEntries);
      foreach (var word in words)
         Console.WriteLine(word);
   }
}
// The example displays the following output:
//       The
//       handsome
//       energetic
//       young
//       dog
//       was
//       playing
//       with
//       his
//       smaller
//       more
//       lethargic
//       litter
//       mate
Module Example
   Public Sub Main()
      Dim separators() As String = {",", ".", "!", "?", ";", ":", " "}
      Dim value As String = "The handsome, energetic, young dog was playing with his smaller, more lethargic litter mate."
      Dim words() As String = value.Split(separators, StringSplitOptions.RemoveEmptyEntries)
      For Each word In words
         Console.WriteLine(word)
      Next   
   End Sub
End Module
' The example displays the following output:
'       The
'       handsome
'       energetic
'       young
'       dog
'       was
'       playing
'       with
'       his
'       smaller
'       more
'       lethargic
'       litter
'       mate

Note that the method is called with the options argument set to StringSplitOptions.RemoveEmptyEntries. This prevents the returned array from including String.Empty values that represent empty substring matches between punctuation marks and white-space characters.

Remarks

When a string is delimited by a known set of strings, you can use the Split method to separate it into substrings.

Return value details

Delimiter strings are not included in the elements of the returned array. For example, if the separator array includes the string "--" and the value of the current string instance is "aa--bb-cc", the method returns an array that contains three elements: "aa", "bb", and "cc".

If this instance does not contain any of the strings in separator, the returned array consists of a single element that contains this instance.

If the options parameter is RemoveEmptyEntries and the length of this instance is zero, the method returns an empty array.

Each element of separator defines a separate delimiter that consists of one or more characters. If the options argument is None, and two delimiters are adjacent or a delimiter is found at the beginning or end of this instance, the corresponding array element contains String.Empty. For example, if separator includes two elements, "-" and "", the value of the string instance is "-_aa-\", and the value of the options argument is None, the method returns a sting array with the following five elements:

  1. String.Empty, which represents the empty string that precedes the "-" substring at index 0.

  2. String.Empty, which represents the empty string between the "-" substring at index 0 and the "_" substring at index 1.

  3. "aa",

  4. String.Empty, which represents the empty string that follows the "_" substring at index 4.

  5. String.Empty, which represents the empty string that follows the "-" substring at index 5.

The separator array

If any of the elements in separator consists of multiple characters, the entire substring is considered a delimiter. For example, if one of the elements in separator is "10", attempting to split the string "This10is10a10string." returns the following four-element array: { "This", "is", "a", "string." }.

If the separator parameter is null or contains no characters, white-space characters are assumed to be the delimiters. White-space characters are defined by the Unicode standard and return true if they are passed to the Char.IsWhiteSpace method.

If the separator parameter in the call to this method overload is null, compiler overload resolution fails. To unambiguously identify the called method, your code must indicate the type of the null. The following example shows several ways to unambiguously identify this overload.

string phrase = "The quick  brown fox";
string[] words;

words = phrase.Split(default(string[]), StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split((string[]) null, StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split(null as string[], StringSplitOptions.RemoveEmptyEntries);
Dim phrase As String = "The quick brown fox"
Dim words() As String

words = phrase.Split(TryCast(Nothing, String()),  
                       StringSplitOptions.RemoveEmptyEntries)

words = phrase.Split(New String() {},
                     StringSplitOptions.RemoveEmptyEntries)

Comparison details

The Split method extracts the substrings in this string that are delimited by one or more of the strings in the separator parameter, and returns those substrings as elements of an array.

The Split method looks for delimiters by performing comparisons using case-sensitive ordinal sort rules. For more information about word, string, and ordinal sorts, see the System.Globalization.CompareOptions enumeration.

The Split method ignores any element of separator whose value is null or the empty string ("").

To avoid ambiguous results when strings in separator have characters in common, the Split operation proceeds from the beginning to the end of the value of the instance, and matches the first element in separator that is equal to a delimiter in the instance. The order in which substrings are encountered in the instance takes precedence over the order of elements in separator.

For example, consider an instance whose value is "abcdef". If the first element in separator was "ef" and the second element was "bcde", the result of the split operation would be a string array that contains two elements, "a" and "f". This is because the substring in the instance, "bcde", is encountered and matches an element in separator before the substring "f" is encountered.

However, if the first element of separator was "bcd" and the second element was "bc", the result of the split operation would be a string array that contains two elements, "a" and "ef". This is because "bcd" is the first delimiter in separator that matches a delimiter in the instance. If the order of the separators was reversed so the first element was "bc" and the second element was "bcd", the result would be a string array that contains two elements, "a" and "def".

Performance considerations

The Split methods allocate memory for the returned array object and a String object for each array element. If your application requires optimal performance or if managing memory allocation is critical in your application, consider using the IndexOf or IndexOfAny method, and optionally the Compare method, to locate a substring within a string.

If you are splitting a string at a separator character, use the IndexOf or IndexOfAny method to locate a separator character in the string. If you are splitting a string at a separator string, use the IndexOf or IndexOfAny method to locate the first character of the separator string. Then use the Compare method to determine whether the characters after that first character are equal to the remaining characters of the separator string.

In addition, if the same set of characters is used to split strings in multiple Split method calls, consider creating a single array and referencing it in each method call. This significantly reduces the additional overhead of each method call.

Notes to Callers

In the .NET Framework 3.5 and earlier versions, if the Split(Char[]) method is passed a separator that is null or contains no characters, the method uses a slightly different set of characters to split the string than the Trim(Char[]) method does to trim the string. In the .NET Framework 4, both methods use an identical set of Unicode white-space characters.

Split(Char[]) Split(Char[]) Split(Char[]) Split(Char[])

Splits a string into substrings that are based on the characters in an array.

public:
 cli::array <System::String ^> ^ Split(... cli::array <char> ^ separator);
public string[] Split (params char[] separator);
member this.Split : char[] -> string[]
Public Function Split (ParamArray separator As Char()) As String()

Parameters

separator
Char[]

A character array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

Returns

String[]

An array whose elements contain the substrings from this instance that are delimited by one or more characters in separator. For more information, see the Remarks section.

Examples

The following example demonstrates how to extract individual words from a block of text by treating white space and punctuation marks as delimiters. The character array passed to the separator parameter of the String.Split(Char[]) method consists of a space character and a tab character, together with some common punctuation symbols.

using System;

public class SplitTest {
    public static void Main() {

        string words = "This is a list of words, with: a bit of punctuation" +
                       "\tand a tab character.";

        string [] split = words.Split(new Char [] {' ', ',', '.', ':', '\t' });

        foreach (string s in split) {

            if (s.Trim() != "")
                Console.WriteLine(s);
        }
    }
}
// The example displays the following output to the console:
//       This
//       is
//       a
//       list
//       of
//       words
//       with
//       a
//       bit
//       of
//       punctuation
//       and
//       a
//       tab
//       character
Public Class SplitTest
    Public Shared Sub Main()
        Dim words As String = "This is a list of words, with: a bit of punctuation" + _
                              vbTab + "and a tab character."
        Dim split As String() = words.Split(New [Char]() {" "c, ","c, "."c, ":"c, CChar(vbTab) })
                
        For Each s As String In  split
            If s.Trim() <> "" Then
                Console.WriteLine(s)
            End If
        Next s
    End Sub 'Main
End Class 'SplitTest
' The example displays the following output to the console:
'       This
'       is
'       a
'       list
'       of
'       words
'       with
'       a
'       bit
'       of
'       punctuation
'       and
'       a
'       tab
'       character

Remarks

When a string is delimited by a known set of characters, you can use the Split(Char[]) method to separate it into substrings. For other ways to extract substrings from a string, see the Alternatives to String.Split section.

Return value details

Delimiter characters are not included in the elements of the returned array. For example, if the separator array includes the character "-" and the value of the current string instance is "aa-bb-cc", the method returns an array that contains three elements: "aa", "bb", and "cc".

If this instance does not contain any of the characters in separator, the returned array consists of a single element that contains this instance.

Each element of separator defines a separate delimiter character. If two delimiters are adjacent, or a delimiter is found at the beginning or end of this instance, the corresponding element in the returned array contains Empty. Here are some examples:

String value Separator Returned array
"42, 12, 19" new Char[] {',', ' '} (C#)

Char() = {","c, " "c}) (Visual Basic)
{"42", "", "12", "", "19"}
"42..12..19" new Char[] {'.'} (C#)

Char() = {"."c} (Visual Basic)
{"42", "", "12", "", "19"}
"Banana" new Char[] {'.'} (C#)

Char() = {"."c} (Visual Basic)
{"Banana"}
"Darb\nSmarba" (C#)

"Darb" & vbLf & "Smarba" (Visual Basic)
new Char[] {} (C#)

Char() = {} (Visual Basic)
{"Darb", "Smarba"}
"Darb\nSmarba" (C#)

"Darb" & vbLf & "Smarba" (Visual Basic)
null (C#)

Nothing (Visual Basic)
{"Darb", "Smarba"}

The separator array

Each element of separator defines a separate delimiter that consists of a single character. If the separator argument is null or contains no characters, the method treats white-space characters as the delimiters. White-space characters are defined by the Unicode standard; they return true if they are passed to the Char.IsWhiteSpace method.

String.Split(Char[]) and compiler overload resolution

Although the single parameter for this overload of String.Split is a character array, you can call it with a single character, as the following example shows.

using System;

public class Example
{
   public static void Main()
   {
      String value = "This is a short string.";
      Char delimiter = 's';
      String[] substrings = value.Split(delimiter);
      foreach (var substring in substrings)
         Console.WriteLine(substring);
   }
}
// The example displays the following output:
//     Thi
//      i
//      a
//     hort
//     tring.
Module Example
   Public Sub Main()
      Dim value As String = "This is a short string."
      Dim delimiter As Char = "s"c
      Dim substrings() As String = value.Split(delimiter)
      For Each substring In substrings
         Console.WriteLine(substring)
      Next
   End Sub
End Module
' The example displays the following output:
'     Thi
'      i
'      a
'     hort
'     tring.

Because the separator parameter is decorated with the ParamArrayAttribute attribute, compilers will interpret a single character as a single-element character array. This is not the case for other String.Split overloads that include a separator parameter; you must explicitly pass these overloads a character array as the separator argument.

Comparison details

The Split(Char[]) method extracts the substrings in this string that are delimited by one or more of the characters in the separator array, and returns those substrings as elements of an array.

The Split(Char[]) method looks for delimiters by performing comparisons using case-sensitive ordinal sort rules. For more information about word, string, and ordinal sorts, see the System.Globalization.CompareOptions enumeration.

Alternatives to String.Split

The Split method is not always the best way to break a delimited string into substrings. If you don't want to extract all of the substrings of a delimited string, or if you want to parse a string based on a pattern instead of a set of delimiter characters, consider the following alternatives.

Regular expressions

If your strings conform to a fixed pattern, you can use a regular expression to extract and handle their elements. For example, if strings take the form "number operand number" you can use a regular expression to extract and handle the string's elements. Here's an example:

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      String[] expressions = { "16 + 21", "31 * 3", "28 / 3",
                               "42 - 18", "12 * 7",
                               "2, 4, 6, 8" };
      String pattern = @"(\d+)\s+([-+*/])\s+(\d+)";
      foreach (var expression in expressions)
         foreach (Match m in Regex.Matches(expression, pattern)) {
            int value1 = Int32.Parse(m.Groups[1].Value);
            int value2 = Int32.Parse(m.Groups[3].Value);
            switch (m.Groups[2].Value)
            {
               case "+":
                  Console.WriteLine("{0} = {1}", m.Value, value1 + value2);
                  break;
               case "-":
                  Console.WriteLine("{0} = {1}", m.Value, value1 - value2);
                  break;
               case "*":
                  Console.WriteLine("{0} = {1}", m.Value, value1 * value2);
                  break;
               case "/":
                  Console.WriteLine("{0} = {1:N2}", m.Value, value1 / value2);
                  break;
            }
         }
   }
}
// The example displays the following output:
//       16 + 21 = 37
//       31 * 3 = 93
//       28 / 3 = 9.33
//       42 - 18 = 24
//       12 * 7 = 84
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
      Dim expressions() As String = { "16 + 21", "31 * 3", "28 / 3",
                                      "42 - 18", "12 * 7",
                                      "2, 4, 6, 8" }

      Dim pattern As String = "(\d+)\s+([-+*/])\s+(\d+)"
      For Each expression In expressions
         For Each m As Match in Regex.Matches(expression, pattern)
            Dim value1 As Integer = Int32.Parse(m.Groups(1).Value)
            Dim value2 As Integer = Int32.Parse(m.Groups(3).Value)
            Select Case m.Groups(2).Value
               Case "+"
                  Console.WriteLine("{0} = {1}", m.Value, value1 + value2)
               Case "-"
                  Console.WriteLine("{0} = {1}", m.Value, value1 - value2)
               Case "*"
                  Console.WriteLine("{0} = {1}", m.Value, value1 * value2)
               Case "/"
                  Console.WriteLine("{0} = {1:N2}", m.Value, value1 / value2)
            End Select
         Next
      Next
   End Sub
End Module
' The example displays the following output:
'       16 + 21 = 37
'       31 * 3 = 93
'       28 / 3 = 9.33
'       42 - 18 = 24
'       12 * 7 = 84

The regular expression pattern (\d+)\s+([-+*/])\s+(\d+) is defined like this:

Pattern Description
(\d+) Match one or more decimal digits. This is the first capturing group.
\s+ Match one or more white-space characters.
([-+*/]) Match an arithmetic operator sign (+, -, *, or /). This is the second capturing group.
\s+ Match one or more white-space characters.
(\d+) Match one or more decimal digits. This is the third capturing group.

You can also use a regular expression to extract substrings from a string based on a pattern rather than a fixed set of characters. This is a common scenario when either of these conditions occurs:

  • One or more of the delimiter characters does not always serve as a delimiter in the String instance.

  • The sequence and number of delimiter characters is variable or unknown.

For example, the Split method cannot be used to split the following string, because the number of \n (in C#) or vbCrLf (in Visual Basic) characters is variable, and they don't always serve as delimiters.


[This is captured\ntext.]\n\n[\n[This is more captured text.]\n]  
\n[Some more captured text:\n   Option1\n   Option2][Terse text.]  

A regular expression can split this string easily, as the following example shows.

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      String input = "[This is captured\ntext.]\n\n[\n" +
                     "[This is more captured text.]\n]\n" +
                     "[Some more captured text:\n   Option1" +
                     "\n   Option2][Terse text.]";
      String pattern = @"\[([^\[\]]+)\]";
      int ctr = 0;
      foreach (Match m in Regex.Matches(input, pattern))
         Console.WriteLine("{0}: {1}", ++ctr, m.Groups[1].Value);
   }
}
// The example displays the following output:
//       1: This is captured
//       text.
//       2: This is more captured text.
//       3: Some more captured text:
//          Option1
//          Option2
//       4: Terse text.
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
      Dim input As String = String.Format("[This is captured{0}text.]" +
                                          "{0}{0}[{0}[This is more " +
                                          "captured text.]{0}{0}" +
                                          "[Some more captured text:" +
                                          "{0}   Option1" +
                                          "{0}   Option2][Terse text.]",
                                          vbCrLf)
      Dim pattern As String = "\[([^\[\]]+)\]"
      Dim ctr As Integer = 0
      For Each m As Match In Regex.Matches(input, pattern)
         ctr += 1
         Console.WriteLine("{0}: {1}", ctr, m.Groups(1).Value)
      Next
   End Sub
End Module
' The example displays the following output:
'       1: This is captured
'       text.
'       2: This is more captured text.
'       3: Some more captured text:
'          Option1
'          Option2
'       4: Terse text.

The regular expression pattern \[([^\[\]]+)\] is defined like this:

Pattern Description
\[ Match an opening bracket.
([^\[\]]+) Match any character that is not an opening or a closing bracket one or more times. This is the first capturing group.
\] Match a closing bracket.

The Regex.Split method is almost identical to String.Split, except that it splits a string based on a regular expression pattern instead of a fixed character set. For example, the following example uses the Regex.Split method to split a string that contains substrings delimited by various combinations of hyphens and other characters.

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      String input = "abacus -- alabaster - * - atrium -+- " +
                     "any -*- actual - + - armoir - - alarm";
      String pattern = @"\s-\s?[+*]?\s?-\s";
      String[] elements = Regex.Split(input, pattern);
      foreach (var element in elements)
         Console.WriteLine(element);
   }
}
// The example displays the following output:
//       abacus
//       alabaster
//       atrium
//       any
//       actual
//       armoir
//       alarm
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
      Dim input As String = "abacus -- alabaster - * - atrium -+- " +
                            "any -*- actual - + - armoir - - alarm"
      Dim pattern As String = "\s-\s?[+*]?\s?-\s"
      Dim elements() As String = Regex.Split(input, pattern)
      For Each element In elements
         Console.WriteLine(element)
      Next
   End Sub
End Module
' The example displays the following output:
'       abacus
'       alabaster
'       atrium
'       any
'       actual
'       armoir
'       alarm

The regular expression pattern \s-\s?[+*]?\s?-\s is defined like this:

Pattern Description
\s- Match a white-space character followed by a hyphen.
\s? Match zero or one white-space character.
[+*]? Match zero or one occurrence of either the + or * character.
\s? Match zero or one white-space character.
-\s Match a hyphen followed by a white-space character.

Search methods and the Substring method

If you aren't interested in all of the substrings in a string, you might prefer to work with one of the string comparison methods that returns the index at which the match begins. You can then call the Substring method to extract the substring that you want. The string comparison methods include:

  • IndexOf, which returns the zero-based index of the first occurrence of a character or string in a string instance.

  • IndexOfAny, which returns the zero-based index in the current string instance of the first occurrence of any character in a character array.

  • LastIndexOf, which returns the zero-based index of the last occurrence of a character or string in a string instance.

  • LastIndexOfAny, which returns a zero-based index in the current string instance of the last occurrence of any character in a character array.

The following example uses the IndexOf method to find the periods in a string. It then uses the Substring method to return full sentences.

using System;
using System.Collections.Generic;

public class Example
{
   public static void Main()
   {
      String value = "This is the first sentence in a string. " +
                     "More sentences will follow. For example, " +
                     "this is the third sentence. This is the " +
                     "fourth. And this is the fifth and final " +
                     "sentence.";
      var sentences = new List<String>();
      int position = 0;
      int start = 0;
      // Extract sentences from the string.
      do {
         position = value.IndexOf('.', start);
         if (position >= 0) {
            sentences.Add(value.Substring(start, position - start + 1).Trim());
            start = position + 1;
         }
      } while (position > 0);

      // Display the sentences.
      foreach (var sentence in sentences)
         Console.WriteLine(sentence);
   }
}
// The example displays the following output:
//       This is the first sentence in a string.
//       More sentences will follow.
//       For example, this is the third sentence.
//       This is the fourth.
//       And this is the fifth and final sentence.
Imports System.Collections.Generic

Module Example
   Public Sub Main()
      Dim value As String = "This is the first sentence in a string. " +
                            "More sentences will follow. For example, " +
                            "this is the third sentence. This is the " +
                            "fourth. And this is the fifth and final " +
                            "sentence."
      Dim sentences As New List(Of String)
      Dim position As Integer = 0
      Dim start As Integer = 0
      ' Extract sentences from the string.
      Do
         position = value.IndexOf("."c, start)
         If position >= 0 Then
            sentences.Add(value.Substring(start, position - start + 1).Trim())
            start = position + 1
         End If
      Loop While position > 0
      
      ' Display the sentences.
      For Each sentence In sentences
         Console.WriteLine(sentence)
      Next
   End Sub
End Module
' The example displays the following output:
'       This is the first sentence in a string.
'       More sentences will follow.
'       For example, this is the third sentence.
'       This is the fourth.
'       And this is the fifth and final sentence.

Performance Considerations

The Split methods allocate memory for the returned array object and a String object for each array element. If your application requires optimal performance or if managing memory allocation is critical in your application, consider using the IndexOf or IndexOfAny method. You also have the option of using the Compare method to locate a substring within a string.

To split a string at a separator character, use the IndexOf or IndexOfAny method to locate a separator character in the string. To split a string at a separator string, use the IndexOf or IndexOfAny method to locate the first character of the separator string. Then use the Compare method to determine whether the characters after that first character are equal to the remaining characters of the separator string.

In addition, if the same set of characters is used to split strings in multiple Split method calls, consider creating a single array and referencing it in each method call. This significantly reduces the additional overhead of each method call.

Notes to Callers

In the .NET Framework 3.5 and earlier versions, if the Split(Char[]) method is passed a separator that is null or contains no characters, the method uses a slightly different set of characters to split the string than the Trim(Char[]) method does to trim the string. In the .NET Framework 4, both methods use an identical set of Unicode white-space characters.

See Also

Split(Char[], StringSplitOptions) Split(Char[], StringSplitOptions) Split(Char[], StringSplitOptions) Split(Char[], StringSplitOptions)

Splits a string into substrings based on the characters in an array. You can specify whether the substrings include empty array elements.

public:
 cli::array <System::String ^> ^ Split(cli::array <char> ^ separator, StringSplitOptions options);
[System.Runtime.InteropServices.ComVisible(false)]
public string[] Split (char[] separator, StringSplitOptions options);
member this.Split : char[] * StringSplitOptions -> string[]
Public Function Split (separator As Char(), options As StringSplitOptions) As String()

Parameters

separator
Char[]

A character array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

options
StringSplitOptions StringSplitOptions StringSplitOptions StringSplitOptions

RemoveEmptyEntries to omit empty array elements from the array returned; or None to include empty array elements in the array returned.

Returns

String[]

An array whose elements contain the substrings in this string that are delimited by one or more characters in separator. For more information, see the Remarks section.

Exceptions

Examples

The following example uses the StringSplitOptions enumeration to include or exclude substrings generated by the Split method.

// This example demonstrates the String.Split(Char[], Boolean) and 
//                               String.Split(Char[], Int32, Boolean) methods
using namespace System;
void Show( array<String^>^entries )
{
   Console::WriteLine( "The return value contains these {0} elements:", entries->Length );
   System::Collections::IEnumerator^ myEnum = entries->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ entry = safe_cast<String^>(myEnum->Current);
      Console::Write( "<{0}>", entry );
   }

   Console::Write( "{0}{0}", Environment::NewLine );
}

int main()
{
   String^ s = ",one,,,two,,,,,three,,";
   array<Char>^sep = gcnew array<Char>{
      ','
   };
   array<String^>^result;
   
   //
   Console::WriteLine( "The original string is \"{0}\".", s );
   Console::WriteLine( "The separation character is '{0}'.", sep[ 0 ] );
   Console::WriteLine();
   
   //
   Console::WriteLine( "Split the string and return all elements:" );
   result = s->Split( sep, StringSplitOptions::None );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return all non-empty elements:" );
   result = s->Split( sep, StringSplitOptions::RemoveEmptyEntries );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return 2 elements:" );
   result = s->Split( sep, 2, StringSplitOptions::None );
   Show( result );
   
   //
   Console::WriteLine( "Split the string and return 2 non-empty elements:" );
   result = s->Split( sep, 2, StringSplitOptions::RemoveEmptyEntries );
   Show( result );
}

/*
This example produces the following results:

The original string is ",one,,,two,,,,,three,,".
The separation character is ','.

Split the string and return all elements:
The return value contains these 12 elements:
<><one><><><two><><><><><three><><>

Split the string and return all non-empty elements:
The return value contains these 3 elements:
<one><two><three>

Split the string and return 2 elements:
The return value contains these 2 elements:
<><one,,,two,,,,,three,,>

Split the string and return 2 non-empty elements:
The return value contains these 2 elements:
<one><,,two,,,,,three,,>

*/
// This example demonstrates the String() methods that use
// the StringSplitOptions enumeration.
using System;

class Sample 
{
    public static void Main() 
    {
    string s1 = ",ONE,,TWO,,,THREE,,";
    string s2 = "[stop]" +
                "ONE[stop][stop]" +
                "TWO[stop][stop][stop]" +
                "THREE[stop][stop]";
    char[] charSeparators = new char[] {','};
    string[] stringSeparators = new string[] {"[stop]"};
    string[] result;
// ------------------------------------------------------------------------------
// Split a string delimited by characters.
// ------------------------------------------------------------------------------
    Console.WriteLine("1) Split a string delimited by characters:\n");

// Display the original string and delimiter characters.
    Console.WriteLine("1a )The original string is \"{0}\".", s1);
    Console.WriteLine("The delimiter character is '{0}'.\n", 
                       charSeparators[0]);

// Split a string delimited by characters and return all elements.
    Console.WriteLine("1b) Split a string delimited by characters and " +
                      "return all elements:");
    result = s1.Split(charSeparators, StringSplitOptions.None);
    Show(result);

// Split a string delimited by characters and return all non-empty elements.
    Console.WriteLine("1c) Split a string delimited by characters and " +
                      "return all non-empty elements:");
    result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the string and empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("1d) Split a string delimited by characters and " +
                      "return 2 elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("1e) Split a string delimited by characters and " +
                      "return 2 non-empty elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// ------------------------------------------------------------------------------
// Split a string delimited by another string.
// ------------------------------------------------------------------------------
    Console.WriteLine("2) Split a string delimited by another string:\n");

// Display the original string and delimiter string.
    Console.WriteLine("2a) The original string is \"{0}\".", s2);
    Console.WriteLine("The delimiter string is \"{0}\".\n", stringSeparators[0]);

// Split a string delimited by another string and return all elements.
    Console.WriteLine("2b) Split a string delimited by another string and " +
                      "return all elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.None);
    Show(result);

// Split the original string at the delimiter and return all non-empty elements.
    Console.WriteLine("2c) Split a string delimited by another string and " +
                      "return all non-empty elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("2d) Split a string delimited by another string and " +
                      "return 2 elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("2e) Split a string delimited by another string and " + 
                      "return 2 non-empty elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);
    }

// Display the array of separated strings.
    public static void Show(string[] entries)
    {
    Console.WriteLine("The return value contains these {0} elements:", entries.Length);
    foreach (string entry in entries)
        {
        Console.Write("<{0}>", entry);
        }
    Console.Write("\n\n");
    }
}
/*
This example produces the following results:

1) Split a string delimited by characters:

1a )The original string is ",ONE,,TWO,,,THREE,,".
The delimiter character is ','.

1b) Split a string delimited by characters and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

1c) Split a string delimited by characters and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

1d) Split a string delimited by characters and return 2 elements:
The return value contains these 2 elements:
<><ONE,,TWO,,,THREE,,>

1e) Split a string delimited by characters and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO,,,THREE,,>

2) Split a string delimited by another string:

2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
The delimiter string is "[stop]".

2b) Split a string delimited by another string and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

2c) Split a string delimited by another string and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

2d) Split a string delimited by another string and return 2 elements:
The return value contains these 2 elements:
<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>

2e) Split a string delimited by another string and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO[stop][stop][stop]THREE[stop][stop]>

*/

' This example demonstrates the String() methods that use
' the StringSplitOptions enumeration.
Imports System

Class Sample
    Public Shared Sub Main() 
        Dim s1 As String = ",ONE,,TWO,,,THREE,,"
        Dim s2 As String = "[stop]" & _
                           "ONE[stop][stop]" & _
                           "TWO[stop][stop][stop]" & _
                           "THREE[stop][stop]"
        Dim charSeparators() As Char = {","c}
        Dim stringSeparators() As String = {"[stop]"}
        Dim result() As String
        ' ------------------------------------------------------------------------------
        ' Split a string delimited by characters.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("1) Split a string delimited by characters:" & vbCrLf)
        
        ' Display the original string and delimiter characters.
        Console.WriteLine("1a )The original string is ""{0}"".", s1)
        Console.WriteLine("The delimiter character is '{0}'." & vbCrLf, charSeparators(0))
        
        ' Split a string delimited by characters and return all elements.
        Console.WriteLine("1b) Split a string delimited by characters and " & _
                          "return all elements:")
        result = s1.Split(charSeparators, StringSplitOptions.None)
        Show(result)
        
        ' Split a string delimited by characters and return all non-empty elements.
        Console.WriteLine("1c) Split a string delimited by characters and " & _
                          "return all non-empty elements:")
        result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' Split the original string into the string and empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("1d) Split a string delimited by characters and " & _
                          "return 2 elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("1e) Split a string delimited by characters and " & _
                          "return 2 non-empty elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' ------------------------------------------------------------------------------
        ' Split a string delimited by another string.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("2) Split a string delimited by another string:" & vbCrLf)
        
        ' Display the original string and delimiter string.
        Console.WriteLine("2a) The original string is ""{0}"".", s2)
        Console.WriteLine("The delimiter string is ""{0}""." & vbCrLf, stringSeparators(0))
        
        ' Split a string delimited by another string and return all elements.
        Console.WriteLine("2b) Split a string delimited by another string and " & _
                          "return all elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string at the delimiter and return all non-empty elements.
        Console.WriteLine("2c) Split a string delimited by another string and " & _
                          "return all non-empty elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
        
        ' Split the original string into the empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("2d) Split a string delimited by another string and " & _
                          "return 2 elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.None)
        Show(result)
        
        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("2e) Split a string delimited by another string and " & _
                          "return 2 non-empty elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)
    
    End Sub 'Main
    
    
    ' Display the array of separated strings.
    Public Shared Sub Show(ByVal entries() As String) 
        Console.WriteLine("The return value contains these {0} elements:", entries.Length)
        Dim entry As String
        For Each entry In  entries
            Console.Write("<{0}>", entry)
        Next entry
        Console.Write(vbCrLf & vbCrLf)
    
    End Sub 'Show
End Class 'Sample
'
'This example produces the following results:
'
'1) Split a string delimited by characters:
'
'1a )The original string is ",ONE,,TWO,,,THREE,,".
'The delimiter character is ','.
'
'1b) Split a string delimited by characters and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'1c) Split a string delimited by characters and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'1d) Split a string delimited by characters and return 2 elements:
'The return value contains these 2 elements:
'<><ONE,,TWO,,,THREE,,>
'
'1e) Split a string delimited by characters and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO,,,THREE,,>
'
'2) Split a string delimited by another string:
'
'2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
'The delimiter string is "[stop]".
'
'2b) Split a string delimited by another string and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'2c) Split a string delimited by another string and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'2d) Split a string delimited by another string and return 2 elements:
'The return value contains these 2 elements:
'<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>
'
'2e) Split a string delimited by another string and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO[stop][stop][stop]THREE[stop][stop]>
'

Remarks

Return value details

Delimiter characters (the characters in the separator array) are not included in the elements of the returned array. For example, if the separator array includes the character "-" and the value of the current string instance is "aa-bb-cc", the method returns an array that contains three elements: "aa", "bb", and "cc".

If this instance does not contain any of the characters in separator, the returned array consists of a single element that contains this instance.

If the options parameter is RemoveEmptyEntries and the length of this instance is zero, the method returns an empty array.

Each element of separator defines a separate delimiter that consists of a single character. If the options argument is None, and two delimiters are adjacent or a delimiter is found at the beginning or end of this instance, the corresponding array element contains String.Empty. For example, if separator includes two elements, "-" and "_", the value of the string instance is "-_aa-_", and the value of the options argument is None, the method returns a string array with the following five elements:

  1. String.Empty, which represents the empty string that precedes the "-" character at index 0.

  2. String.Empty, which represents the empty string between the "-" character at index 0 and the "_" character at index 1.

  3. "aa",

  4. String.Empty, which represents the empty string that follows the "_" character at index 4.

  5. String.Empty, which represents the empty string that follows the "-" character at index 5.

The separator array

If the separator parameter is null or contains no characters, white-space characters are assumed to be the delimiters. White-space characters are defined by the Unicode standard and return true if they are passed to the Char.IsWhiteSpace method.

If the separator parameter in the call to this method overload is null, compiler overload resolution fails. To unambiguously identify the called method, your code must indicate the type of the null. The following example shows several ways to unambiguously identify this overload.

string phrase = "The quick  brown fox";
string[] words;

words = phrase.Split(default(Char[]), StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split((char[]) null, StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split(null as char[], StringSplitOptions.RemoveEmptyEntries);
Dim phrase As String = "The quick brown fox"
Dim words() As String

words = phrase.Split(TryCast(Nothing, Char()),  
                       StringSplitOptions.RemoveEmptyEntries)

words = phrase.Split(New Char() {}, 
                     StringSplitOptions.RemoveEmptyEntries)

Comparison details

The Split method extracts the substrings in this string that are delimited by one or more of the characters in the separator parameter, and returns those substrings as elements of an array.

The Split method looks for delimiters by performing comparisons using case-sensitive ordinal sort rules. For more information about word, string, and ordinal sorts, see the System.Globalization.CompareOptions enumeration.

Performance Considerations

The Split methods allocate memory for the returned array object and a String object for each array element. If your application requires optimal performance or if managing memory allocation is critical in your application, consider using the IndexOf or IndexOfAny method, and optionally the Compare method, to locate a substring within a string.

If you are splitting a string at a separator character, use the IndexOf or IndexOfAny method to locate a separator character in the string. If you are splitting a string at a separator string, use the IndexOf or IndexOfAny method to locate the first character of the separator string. Then use the Compare method to determine whether the characters after that first character are equal to the remaining characters of the separator string.

In addition, if the same set of characters is used to split strings in multiple Split method calls, consider creating a single array and referencing it in each method call. This significantly reduces the additional overhead of each method call.

Notes to Callers

In the .NET Framework 3.5 and earlier versions, if the Split(Char[]) method is passed a separator that is null or contains no characters, the method uses a slightly different set of characters to split the string than the Trim(Char[]) method does to trim the string. In the .NET Framework 4, both methods use an identical set of Unicode white-space characters.

Split(Char[], Int32) Split(Char[], Int32) Split(Char[], Int32) Split(Char[], Int32)

Splits a string into a maximum number of substrings based on the characters in an array. You also specify the maximum number of substrings to return.

public:
 cli::array <System::String ^> ^ Split(cli::array <char> ^ separator, int count);
public string[] Split (char[] separator, int count);
member this.Split : char[] * int -> string[]
Public Function Split (separator As Char(), count As Integer) As String()

Parameters

separator
Char[]

A character array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

count
Int32 Int32 Int32 Int32

The maximum number of substrings to return.

Returns

String[]

An array whose elements contain the substrings in this instance that are delimited by one or more characters in separator. For more information, see the Remarks section.

Exceptions

Examples

The following example demonstrates how count affects the number of strings returned by Split.

using System;

public class Example
{
   public static void Main() 
   {
      string delimStr = " ,.:";
      char [] delimiter = delimStr.ToCharArray();
      string words = "one two,three:four.";
      string [] split = null;

      Console.WriteLine("The delimiters are -{0}-", delimStr);
      for (int x = 1; x <= 5; x++) {
         split = words.Split(delimiter, x);
         Console.WriteLine("\ncount = {0,2} ..............", x);
         foreach (var s in split) {
             Console.WriteLine("-{0}-", s);
         }
      }
   }
}
// The example displays the following output:
//       The delimiters are - ,.:-
//       count =  1 ..............
//       -one two,three:four.-
//       count =  2 ..............
//       -one-
//       -two,three:four.-
//       count =  3 ..............
//       -one-
//       -two-
//       -three:four.-
//       count =  4 ..............
//       -one-
//       -two-
//       -three-
//       -four.-
//       count =  5 ..............
//       -one-
//       -two-
//       -three-
//       -four-
//       --
Public Class StringSplit2
   Public Shared Sub Main()
      
      Dim delimStr As String = " ,.:"
      Dim delimiter As Char() = delimStr.ToCharArray()
      Dim words As String = "one two,three:four."
      Dim split As String() = Nothing
      
      Console.WriteLine("The delimiters are -{0}-", delimStr)
      Dim x As Integer
      For x = 1 To 5
         split = words.Split(delimiter, x)
         Console.WriteLine(ControlChars.Cr + "count = {0,2} ..............", x)
         Dim s As String
         For Each s In  split
            Console.WriteLine("-{0}-", s)
         Next s
      Next x
   End Sub 
End Class 
' The example displays the following output:
'       The delimiters are - ,.:-
'       count =  1 ..............
'       -one two,three:four.-
'       count =  2 ..............
'       -one-
'       -two,three:four.-
'       count =  3 ..............
'       -one-
'       -two-
'       -three:four.-
'       count =  4 ..............
'       -one-
'       -two-
'       -three-
'       -four.-
'       count =  5 ..............
'       -one-
'       -two-
'       -three-
'       -four-
'       --

Remarks

Delimiter characters are not included in the elements of the returned array.

If this instance does not contain any of the characters in separator, the returned array consists of a single element that contains this instance. If count is zero, an empty array is returned.

If the separator parameter is null or contains no characters, white-space characters are assumed to be the delimiters. White-space characters are defined by the Unicode standard and return true if they are passed to the Char.IsWhiteSpace method.

Each element of separator defines a separate delimiter character. If two delimiters are adjacent, or a delimiter is found at the beginning or end of this instance, the corresponding array element contains Empty.

If there are more than count substrings in this instance, the first count minus 1 substrings are returned in the first count minus 1 elements of the return value, and the remaining characters in this instance are returned in the last element of the return value.

If count is greater than the number of substrings, the available substrings are returned and no exception is thrown.

The following table provides examples.

String value Separator Count Returned array
"42, 12, 19" new Char[] {',', ' '} (C#)

Char() = {","c, " "c} (Visual Basic)
2 {"42", " 12, 19"}
"42..12..19" new Char[] {'.'} (C#)

Char() = {"."c} (Visual Basic)
4 {"42", "", "12", ".19"}
"Banana" new Char[] {'.'} (C#)

Char() = {"."c} (Visual Basic)
2 {"Banana"}
"Darb\nSmarba" (C#)

"Darb" & vbLf & "Smarba" (Visual Basic)
new Char[] {} (C#)

Char() = {} (Visual Basic)
1 {"Darb\nSmarba"} (C#)

"Darb" & vbLf & "Smarba" (Visual Basic)
"Darb\nSmarba" (C#)

"Darb" & vbLf & "Smarba" (Visual Basic)
new Char[] null (C#)

Char() = Nothing
2 {"Darb", "Smarba"}
"Darb\nSmarba" (C#)

"Darb" & vbLf & "Smarba" (Visual Basic)
new Char[] null (C#)

Char() = Nothing
100 {"Darb", "Smarba"}

Performance Considerations

The Split methods allocate memory for the returned array object and a String object for each array element. If your application requires optimal performance or if managing memory allocation is critical in your application, consider using the IndexOf or IndexOfAny method, and optionally the Compare method, to locate a substring within a string.

If you are splitting a string at a separator character, use the IndexOf or IndexOfAny method to locate a separator character in the string. If you are splitting a string at a separator string, use the IndexOf or IndexOfAny method to locate the first character of the separator string. Then use the Compare method to determine whether the characters after that first character are equal to the remaining characters of the separator string.

In addition, if the same set of characters is used to split strings in multiple Split method calls, consider creating a single array and referencing it in each method call. This significantly reduces the additional overhead of each method call.

Notes to Callers

In the .NET Framework 3.5 and earlier versions, if the Split(Char[]) method is passed a separator that is null or contains no characters, the method uses a slightly different set of characters to split the string than the Trim(Char[]) method does to trim the string. In the .NET Framework 4, both methods use an identical set of Unicode white-space characters.

See Also

Split(Char, StringSplitOptions) Split(Char, StringSplitOptions) Split(Char, StringSplitOptions)

public string[] Split (char separator, StringSplitOptions options = System.StringSplitOptions.None);
member this.Split : char * StringSplitOptions -> string[]
Public Function Split (separator As Char, Optional options As StringSplitOptions = System.StringSplitOptions.None) As String()

Parameters

separator
Char Char Char Char

Returns

String[]

Split(String, StringSplitOptions) Split(String, StringSplitOptions) Split(String, StringSplitOptions)

public string[] Split (string separator, StringSplitOptions options = System.StringSplitOptions.None);
member this.Split : string * StringSplitOptions -> string[]
Public Function Split (separator As String, Optional options As StringSplitOptions = System.StringSplitOptions.None) As String()

Parameters

Returns

String[]

Applies to