String.Contains 方法

参考

定义

命名空间:: System

程序集:: System.Runtime.dll

程序集:: netstandard.dll

程序集:: mscorlib.dll

重要

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重载

Contains(Char)	返回一个值，该值指示指定的字符是否出现在此字符串中。
Contains(String)	返回一个值，该值指示指定的子串是否出现在此字符串中。
Contains(Char, StringComparison)	使用指定的比较规则返回一个值，该值指示指定的字符是否出现在此字符串中。
Contains(String, StringComparison)	使用指定的比较规则返回一个值，该值指示指定的字符串是否出现在此字符串中。

Contains(Char)

Source:: String.Searching.cs

Source:: String.Searching.cs

Source:: String.Searching.cs

返回一个值，该值指示指定的字符是否出现在此字符串中。

public:
 bool Contains(char value);

public bool Contains (char value);

member this.Contains : char -> bool

Public Function Contains (value As Char) As Boolean

参数

value: Char

要查找的字符。

Boolean

如果 value 参数在此字符串中出现，则为 true；否则为 false。

注解

此方法执行区分大小写和不区分区域性的序号 () 比较。

适用于

Contains(String)

Source:: String.Searching.cs

Source:: String.Searching.cs

Source:: String.Searching.cs

返回一个值，该值指示指定的子串是否出现在此字符串中。

public:
 bool Contains(System::String ^ value);

public bool Contains (string value);

member this.Contains : string -> bool

Public Function Contains (value As String) As Boolean

参数

value: String

要搜寻的字符串。

Boolean

如果 true 参数出现在此字符串中，或者 value 为空字符串 ("")，则为 value；否则为 false。

例外

ArgumentNullException

value 为 null。

示例

以下示例确定字符串“fox”是否是熟悉的引用的子字符串。如果在字符串中找到“fox”，则它还会显示其起始位置。

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

let s1 = "The quick brown fox jumps over the lazy dog"
let s2 = "fox"
let b = s1.Contains s2
printfn $"'{s2}' is in the string '{s1}': {b}"
if b then
    let index = s1.IndexOf s2
    if index >= 0 then
        printfn $"'{s2} begins at character position {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

注解

此方法执行区分大小写和不区分区域性的序号 () 比较。搜索从此字符串的第一个字符位置开始，并一直持续到最后一个字符位置。

执行区分区域性或不区分大小写的序号比较：

在 .NET Core 2.1 及更高版本上：请改为调用 Contains(String, StringComparison) 重载。
在 .NET Framework：创建自定义方法。以下示例演示了一种此类方法。它定义一个 String 包含 StringComparison 参数的扩展方法，并指示在使用指定形式的字符串比较时，字符串是否包含子字符串。

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;                      
   }
}

open System
open System.Runtime.CompilerServices

[<Extension>]
type StringExtensions =
    [<Extension>]
    static member Contains(str: string, substring, comp: StringComparison) =
        if substring = null then
            invalidArg "substring" "substring cannot be null"
        if Enum.IsDefined(typeof<StringComparison>, comp) |> not then
            invalidArg "comp" "comp is not a member of StringComparison"
        str.IndexOf(substring, comp) >= 0

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

let s = "This is a string."
let sub1 = "this"
printfn $"Does '{s}' contain '{sub1}'?"
let comp = StringComparison.Ordinal
printfn $"   {comp:G}: {s.Contains(sub1, comp)}"

let comp2 = StringComparison.OrdinalIgnoreCase
printfn $"   {comp2:G}: {s.Contains(sub1, comp2)}"

// The example displays the following output:
//       Does 'This is a string.' contain 'this'?
//          Ordinal: False
//          OrdinalIgnoreCase: True

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

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

如果对子字符串 value 在当前实例中的位置感兴趣，可以调用 IndexOf 方法来获取其第一个匹配项的起始位置，也可以调用 LastIndexOf 方法来获取其最后一个匹配项的起始位置。该示例包括在字符串实例中找到子字符串时对 IndexOf(String) 方法的调用。

另请参阅

适用于

Contains(Char, StringComparison)

Source:: String.Searching.cs

Source:: String.Searching.cs

Source:: String.Searching.cs

使用指定的比较规则返回一个值，该值指示指定的字符是否出现在此字符串中。

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

参数

value: Char

要查找的字符。

comparisonType: StringComparison

一个枚举值，用于指定比较中要使用的规则。

Boolean

如果 value 参数在此字符串中出现，则为 true；否则为 false。

适用于

Contains(String, StringComparison)

Source:: String.Searching.cs

Source:: String.Searching.cs

Source:: String.Searching.cs

使用指定的比较规则返回一个值，该值指示指定的字符串是否出现在此字符串中。

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

参数

value: String

要搜寻的字符串。

comparisonType: StringComparison

一个枚举值，用于指定比较中要使用的规则。

Boolean

如果 true 参数出现在此字符串中，或者 value 为空字符串 ("")，则为 value；否则为 false。

适用于

String.Contains 方法

定义

重载

Contains(Char)

参数

返回

注解

适用于

Contains(String)

参数

返回

例外

示例

注解

另请参阅

适用于

Contains(Char, StringComparison)

参数

返回

适用于

Contains(String, StringComparison)

参数

返回

适用于

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