String.Contains Method

Definition

Overloads

Contains(Char, StringComparison)

Returns a value indicating whether a specified character occurs within this string, using the specified comparison rules.

Contains(Char)

Returns a value indicating whether a specified character occurs within this string.

Contains(String)

Returns a value indicating whether a specified substring occurs within this string.

Contains(String, StringComparison)

Returns a value indicating whether a specified string occurs within this string, using the specified comparison rules.

Contains(Char, StringComparison)

Returns a value indicating whether a specified character occurs within this string, using the specified comparison rules.

public:
 bool Contains(char value, StringComparison comparisonType);
public bool Contains (char value, StringComparison comparisonType);
member this.Contains : char * StringComparison -> bool
Public Function Contains (value As Char, comparisonType As StringComparison) As Boolean

Parameters

value
Char

The character to seek.

comparisonType
StringComparison

One of the enumeration values that specifies the rules to use in the comparison.

Returns

Boolean

true if the value parameter occurs within this string; otherwise, false.

Applies to

Contains(Char)

Returns a value indicating whether a specified character occurs within this string.

public:
 bool Contains(char value);
public bool Contains (char value);
member this.Contains : char -> bool
Public Function Contains (value As Char) As Boolean

Parameters

value
Char

The character to seek.

Returns

Boolean

true if the value parameter occurs within this string; otherwise, false.

Remarks

This method performs an ordinal (case-sensitive and culture-insensitive) comparison.

Applies to

Contains(String)

Returns a value indicating whether a specified substring occurs within this string.

public:
 bool Contains(System::String ^ value);
public bool Contains (string value);
member this.Contains : string -> bool
Public Function Contains (value As String) As Boolean

Parameters

value
String

The string to seek.

Returns

Boolean

true if the value parameter occurs within this string, or if value is the empty string (""); otherwise, false.

Exceptions

value is null.

Examples

The following example determines whether the string "fox" is a substring of a familiar quotation. If "fox" is found in the string, it also displays its starting position.

using namespace System;

int main()
{
   String^ s1 = "The quick brown fox jumps over the lazy dog";
   String^ s2 = "fox";
   bool b = s1->Contains( s2 );
   Console::WriteLine( "Is the string, s2, in the string, s1?: {0}", b );
   if (b) {
      int index = s1->IndexOf(s2);
      if (index >= 0)
         Console::WriteLine("'{0} begins at character position {1}",
                            s2, index + 1);
   }
}
// This example displays the following output:
//    'fox' is in the string 'The quick brown fox jumps over the lazy dog': True
//    'fox begins at character position 17
string s1 = "The quick brown fox jumps over the lazy dog";
string s2 = "fox";
bool b = s1.Contains(s2);
Console.WriteLine("'{0}' is in the string '{1}': {2}",
                s2, s1, b);
if (b) {
    int index = s1.IndexOf(s2);
    if (index >= 0)
        Console.WriteLine("'{0} begins at character position {1}",
                      s2, index + 1);
}
// This example displays the following output:
//    'fox' is in the string 'The quick brown fox jumps over the lazy dog': True
//    'fox begins at character position 17
Class Example
   Public Shared Sub Main()
      Dim s1 As String = "The quick brown fox jumps over the lazy dog"
      Dim s2 As String = "fox"
      Dim b As Boolean = s1.Contains(s2)
      Console.WriteLine("'{0}' is in the string '{1}': {2}",
                        s2, s1, b)
      If b Then
          Dim index As Integer = s1.IndexOf(s2)
          If index >= 0 Then
             Console.WriteLine("'{0} begins at character position {1}",
                               s2, index + 1)
          End If
       End If
   End Sub
End Class
'
' This example displays the following output:
'    'fox' is in the string 'The quick brown fox jumps over the lazy dog': True
'    'fox begins at character position 17

Remarks

This method performs an ordinal (case-sensitive and culture-insensitive) comparison. The search begins at the first character position of this string and continues through the last character position.

To perform a culture-sensitive or ordinal case-insensitive comparison:

  • On .NET Core 2.1 and later versions: Call the Contains(Char, StringComparison) overload instead.

  • On .NET Framework: Create a custom method. The following example illustrates one such approach. It defines a String extension method that includes a StringComparison parameter and indicates whether a string contains a substring when using the specified form of string comparison.

    using System;
    
    public static class StringExtensions
    {
       public static bool Contains(this String str, String substring, 
                                   StringComparison comp)
       {                            
            if (substring == null)
                throw new ArgumentNullException("substring", 
                                             "substring cannot be null.");
            else if (! Enum.IsDefined(typeof(StringComparison), comp))
                throw new ArgumentException("comp is not a member of StringComparison",
                                         "comp");
    
            return str.IndexOf(substring, comp) >= 0;                      
       }
    }
    
    Imports System.Runtime.CompilerServices
    
    Module StringExtensions
       <Extension()>
       Public Function Contains(str As String, substring As String, 
                                comp As StringComparison) As Boolean
          If substring Is Nothing Then
             Throw New ArgumentNullException("substring", 
                                             "substring cannot be null.")
          Else If Not [Enum].IsDefined(GetType(StringComparison), comp)
             Throw New ArgumentException("comp is not a member of StringComparison",
                                         "comp")
          End If                               
          Return str.IndexOf(substring, comp) >= 0                      
       End Function
    End Module
    

    The following example then calls the Contains extension method to determine whether a substring is found in a string when using ordinal comparison and case-insensitive ordinal comparison.

    String s = "This is a string.";
    String sub1 = "this";
    Console.WriteLine("Does '{0}' contain '{1}'?", s, sub1);
    StringComparison comp = StringComparison.Ordinal;
    Console.WriteLine("   {0:G}: {1}", comp, s.Contains(sub1, comp));
    
    comp = StringComparison.OrdinalIgnoreCase;
    Console.WriteLine("   {0:G}: {1}", comp, s.Contains(sub1, comp));
    
    // The example displays the following output:
    //       Does 'This is a string.' contain 'this'?
    //          Ordinal: False
    //          OrdinalIgnoreCase: True
    
    Public Module Example
       Public Sub Main
          Dim s As String = "This is a string."
          Dim sub1 As String = "this"
          Console.WriteLine("Does '{0}' contain '{1}'?", s, sub1)
          Dim comp As StringComparison = StringComparison.Ordinal
          Console.WriteLine("   {0:G}: {1}", comp, s.Contains(sub1, comp))
          
          comp = StringComparison.OrdinalIgnoreCase
          Console.WriteLine("   {0:G}: {1}", comp, s.Contains(sub1, comp))
       End Sub
    End Module
    ' The example displays the following output:
    '       Does 'This is a string.' contain 'this'?
    '          Ordinal: False
    '          OrdinalIgnoreCase: True
    

See also

Applies to

Contains(String, StringComparison)

Returns a value indicating whether a specified string occurs within this string, using the specified comparison rules.

public:
 bool Contains(System::String ^ value, StringComparison comparisonType);
public bool Contains (string value, StringComparison comparisonType);
member this.Contains : string * StringComparison -> bool
Public Function Contains (value As String, comparisonType As StringComparison) As Boolean

Parameters

value
String

The string to seek.

comparisonType
StringComparison

One of the enumeration values that specifies the rules to use in the comparison.

Returns

Boolean

true if the value parameter occurs within this string, or if value is the empty string (""); otherwise, false.

Applies to