String.Contains String.Contains String.Contains String.Contains Method

定義

多載

Contains(Char) Contains(Char) Contains(Char) Contains(Char)
Contains(String) Contains(String) Contains(String) Contains(String)

傳回值,這個值表示指定的子字串是否會出現在這個字串內。Returns a value indicating whether a specified substring occurs within this string.

Contains(Char, StringComparison) Contains(Char, StringComparison) Contains(Char, StringComparison) Contains(Char, StringComparison)
Contains(String, StringComparison) Contains(String, StringComparison) Contains(String, StringComparison) Contains(String, StringComparison)

Contains(Char) Contains(Char) Contains(Char) Contains(Char)

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

參數

value
Char Char Char Char

傳回

Contains(String) Contains(String) Contains(String) Contains(String)

傳回值,這個值表示指定的子字串是否會出現在這個字串內。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

參數

value
String String String String

要搜尋的字串。The string to seek.

傳回

如果 true 參數出現在這個字串內,或是 value 為空字串 (""),則為 value,否則為 falsetrue if the value parameter occurs within this string, or if value is the empty string (""); otherwise, false.

例外狀況

範例

下列範例會判斷熟悉引號的子字串是否包含"fox"的字串。The following example determines whether the string "fox" is a substring of a familiar quotation. 如果字串中找到"fox",它也會顯示其起始位置。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
using System;

class Example
{
    public static void Main() 
    {
       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 display 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

備註

這個方法會執行序數 (區分大小寫且區分文化特性) 比較。This method performs an ordinal (case-sensitive and culture-insensitive) comparison. 搜尋這個字串的第一個字元位置開始,然後繼續進行到最後一個字元位置。The search begins at the first character position of this string and continues through the last character position.

若要判斷字串是否包含指定的子字串使用序數比較 (例如,區分文化特性的比較或不區分大小寫的序數比較) 以外的項目,您可以建立自訂的方法。To determine whether a string contains a specified substring by using something other than ordinal comparison (such as culture-sensitive comparison, or ordinal case-insensitive comparison), you can create a custom method. 下列範例說明這類方法之一。The following example illustrates one such approach. 它會定義String擴充方法,其中包含StringComparison參數,並指出字串是否包含子字串,使用指定的格式的字串比較時。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

下列範例會接著呼叫Contains延伸模組方法,以判斷子字串是否要使用序數比較和區分大小寫的序數比較時的字串中找到。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.

using System;

public class Example
{
   public static void Main()
   {
      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

如果您有興趣的子字串的位置value在目前的執行個體,您可以呼叫IndexOf可以呼叫方法來取得其第一個項目,或您的開始位置LastIndexOf方法來取得的起始位置及其上一次。If you are interested in the position of the substring value in the current instance, you can call the IndexOf method to get the starting position of its first occurrence, or you can call the LastIndexOf method to get the starting position of its last occurrence. 此範例包括呼叫IndexOf(String)方法如果在字串執行個體中找到的子字串。The example includes a call to the IndexOf(String) method if a substring is found in a string instance.

另請參閱

Contains(Char, StringComparison) Contains(Char, StringComparison) Contains(Char, StringComparison) Contains(Char, StringComparison)

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

參數

value
Char Char Char Char

傳回

Contains(String, StringComparison) Contains(String, StringComparison) Contains(String, StringComparison) Contains(String, StringComparison)

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

參數

傳回

適用於