String.Contains 方法

定義

命名空間:

System

組件:

netstandard.dll, System.Runtime.dll

多載

名稱	Description
Contains(String, StringComparison)	回傳一個值，表示指定字串是否出現在該字串中，並使用指定的比較規則。
Contains(Char, StringComparison)	回傳一個值，表示指定字元是否出現在該字串中，並使用指定的比較規則。
Contains(String)	回傳一個值，表示指定子字串是否出現在此字串中。
Contains(Char)	回傳一個值，表示指定字元是否出現在該字串中。

Contains(String, StringComparison)

來源:

String.Searching.cs

回傳一個值，表示指定字串是否出現在該字串中，並使用指定的比較規則。

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

value

String

那條線要尋找。

comparisonType

StringComparison

其中一個列舉值，用來指定比較時要使用的規則。

傳回

Boolean

true若參數value出現在此字串內，或value為空字串（“”）;否則，。 false

Contains(Char, StringComparison)

來源:

String.Searching.cs

回傳一個值，表示指定字元是否出現在該字串中，並使用指定的比較規則。

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

值得尋找的角色。

comparisonType

StringComparison

其中一個列舉值，用來指定比較時要使用的規則。

傳回

Boolean

true若參數value位於此字串內;否則，。 false

Contains(String)

來源:

String.Searching.cs

回傳一個值，表示指定子字串是否出現在此字串中。

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

public bool Contains(string value);

member this.Contains : string -> bool

Public Function Contains (value As String) As Boolean

參數

value

String

那條線要尋找。

傳回

Boolean

true若參數value出現在此字串內，或value為空字串（“”）;否則，。 false

例外狀況

ArgumentNullException

value 為 null。

範例

以下範例判斷字串「fox」是否為熟悉引號的子字串。 若字串中出現「fox」，則會顯示起始位置。

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

備註

此方法進行序數比較（大小寫區分且不影響文化）。 搜尋從該字串的第一個字元位置開始，並持續到最後一個字元的位置。

要進行培養敏感或序數大小寫不敏感的比較：

• 在 .NET Core 2.1 及更新版本中：改為呼叫過載。Contains(String, StringComparison)

• 在 .NET Framework 上：建立自訂方法。 以下範例說明其中一種方法。 它定義了一種 String 擴充方法，包含參數 StringComparison ，並指示字串在使用指定字串比較形式時是否包含子字串。

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

如果你想知道子字串 value 在當前實例中的位置，你可以呼叫 IndexOf 方法取得它第一次出現的起始位置，或者 LastIndexOf 呼叫方法取得它最後出現時的起始位置。 範例中包含若在字串實例中發現子字串時呼叫該 IndexOf(String) 方法。

另請參閱

• IndexOf(Char)
• LastIndexOf(String)

Contains(Char)

來源:

String.Searching.cs

回傳一個值，表示指定字元是否出現在該字串中。

public:
 bool Contains(char value);

public bool Contains(char value);

member this.Contains : char -> bool

Public Function Contains (value As Char) As Boolean

參數

value

Char

值得尋找的角色。

傳回

Boolean

true若參數value位於此字串內;否則，。 false

備註

此方法進行序數比較（大小寫區分且不影響文化）。