String.Join 方法

连接对象数组的字符串表示形式，其中在每个成员之间使用指定的分隔符。Concatenates the string representations of an array of objects, using the specified separator between each member.

public:
 static System::String ^ Join(char separator, ... cli::array <System::Object ^> ^ values);

public static string Join (char separator, params object[] values);

static member Join : char * obj[] -> string

Public Shared Function Join (separator As Char, ParamArray values As Object()) As String

参数

返回

异常

连接字符串数组，其中在每个成员之间使用指定的分隔符。Concatenates an array of strings, using the specified separator between each member.

public:
 static System::String ^ Join(char separator, ... cli::array <System::String ^> ^ value);

public static string Join (char separator, params string[] value);

static member Join : char * string[] -> string

Public Shared Function Join (separator As Char, ParamArray value As String()) As String

参数

返回

异常

串联类型为 IEnumerable<T> 的 String 构造集合的成员，其中在每个成员之间使用指定的分隔符。Concatenates the members of a constructed IEnumerable<T> collection of type String, using the specified separator between each member.

public:
 static System::String ^ Join(System::String ^ separator, System::Collections::Generic::IEnumerable<System::String ^> ^ values);

[System.Runtime.InteropServices.ComVisible(false)]
public static string Join (string separator, System.Collections.Generic.IEnumerable<string> values);

static member Join : string * seq<string> -> string

Public Shared Function Join (separator As String, values As IEnumerable(Of String)) As String

参数

返回

属性

ComVisibleAttribute

异常

示例

下面的示例使用埃拉托色 of 尼斯筛法算法来计算小于或等于100的质数。The following example uses the Sieve of Eratosthenes algorithm to calculate the prime numbers that are less than or equal to 100. 它将结果分配给类型 String的 List<T> 对象，然后将其传递给 Join(String, IEnumerable<String>) 方法。It assigns the result to a List<T> object of type String, which it then passes to the Join(String, IEnumerable<String>) method.

using System;
using System.Collections.Generic;

public class Example
{
   public static void Main()
   {
      int maxPrime = 100;
      List<int> primes = GetPrimes(maxPrime);
      Console.WriteLine("Primes less than {0}:", maxPrime);
      Console.WriteLine("   {0}", String.Join(" ", primes));
   }

   private static List<int> GetPrimes(int maxPrime)
   {
      Array values = Array.CreateInstance(typeof(int), 
                              new int[] { maxPrime - 1}, new int[] { 2 });
      // Use Sieve of Eratosthenes to determine prime numbers.
      for (int ctr = values.GetLowerBound(0); ctr <= (int) Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))); ctr++)
      {
                           
         if ((int) values.GetValue(ctr) == 1) continue;
         
         for (int multiplier = ctr; multiplier <=  maxPrime / 2; multiplier++)
            if (ctr * multiplier <= maxPrime)
               values.SetValue(1, ctr * multiplier);
      }      
      
      List<int> primes = new List<int>();
      for (int ctr = values.GetLowerBound(0); ctr <= values.GetUpperBound(0); ctr++)
         if ((int) values.GetValue(ctr) == 0) 
            primes.Add(ctr);
      return primes;
   }   
}
// The example displays the following output:
//    Primes less than 100:
//       2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Imports System.Collections.Generic

Module Example
   Public Sub Main()
      Dim maxPrime As Integer = 100
      Dim primes As List(Of String) = GetPrimes(maxPrime)
      Console.WriteLine("Primes less than {0}:", maxPrime)
      Console.WriteLine("   {0}", String.Join(" ", primes))
   End Sub
   
   Private Function GetPrimes(maxPrime As Integer) As List(Of String)
      Dim values As Array = Array.CreateInstance(GetType(Integer), _
                              New Integer() { maxPrime - 1}, New Integer(){ 2 }) 
        ' Use Sieve of Eratosthenes to determine prime numbers.
      For ctr As Integer = values.GetLowerBound(0) To _
                           CInt(Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))))
         If CInt(values.GetValue(ctr)) = 1 Then Continue For
         
         For multiplier As Integer = ctr To maxPrime \ 2
            If ctr * multiplier <= maxPrime Then values.SetValue(1, ctr * multiplier)
         Next   
      Next      
      
      Dim primes As New List(Of String)
      For ctr As Integer = values.GetLowerBound(0) To values.GetUpperBound(0)
         If CInt(values.GetValue(ctr)) = 0 Then primes.Add(ctr.ToString())
      Next            
      Return primes
   End Function   
End Module
' The example displays the following output:
'    Primes less than 100:
'       2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

注解

如果 null``separator，则改为使用空字符串（String.Empty）。If separator is null, an empty string (String.Empty) is used instead. 如果 null``values 的任何成员，则改为使用空字符串。If any member of values is null, an empty string is used instead.

Join(String, IEnumerable<String>) 是一种简便方法，使你可以连接 IEnumerable(Of String) 集合中的每个元素，而无需先将元素转换为字符串数组。Join(String, IEnumerable<String>) is a convenience method that lets you concatenate each element in an IEnumerable(Of String) collection without first converting the elements to a string array. 它对语言集成查询（LINQ）查询表达式特别有用。It is particularly useful with Language-Integrated Query (LINQ) query expressions. 下面的示例将包含字母表的大写或小写字母的 List(Of String) 对象传递到 lambda 表达式，该表达式选择等于或大于特定字母的字母（在本例中为 "M"）。The following example passes a List(Of String) object that contains either the uppercase or lowercase letters of the alphabet to a lambda expression that selects letters that are equal to or greater than a particular letter (which, in the example, is "M"). Enumerable.Where 方法返回的 IEnumerable(Of String) 集合会传递到 Join(String, IEnumerable<String>) 方法，以单个字符串的形式显示结果。The IEnumerable(Of String) collection returned by the Enumerable.Where method is passed to the Join(String, IEnumerable<String>) method to display the result as a single string.

using System;
using System.Collections.Generic;
using System.Linq;

public class Example
{
   public static void Main()
   {
      string output = String.Join(" ", GetAlphabet(true).Where( letter => 
                      letter.CompareTo("M") >= 0));
      Console.WriteLine(output);  
   }

   private static List<string> GetAlphabet(bool upper)
   {
      List<string> alphabet = new List<string>();
      int charValue = upper ? 65 : 97;
      for (int ctr = 0; ctr <= 25; ctr++)
         alphabet.Add(Convert.ToChar(charValue + ctr).ToString());
      return alphabet; 
   }
}
// The example displays the following output:
//      M N O P Q R S T U V W X Y Z

Imports System.Collections.Generic
Imports System.Linq

Module modMain
   Public Sub Main()
      Dim output As String = String.Join(" ", GetAlphabet(True).Where(Function(letter) _
                                                         letter >= "M"))
        
      Console.WriteLine(output)                                     
   End Sub
   
   Private Function GetAlphabet(upper As Boolean) As List(Of String)
      Dim alphabet As New List(Of String)
      Dim charValue As Integer = CInt(IIf(upper, 65, 97))
      For ctr As Integer = 0 To 25
         alphabet.Add(ChrW(charValue + ctr).ToString())
      Next
      Return alphabet 
   End Function
End Module
' The example displays the following output:
'      M N O P Q R S T U V W X Y Z

另请参阅

• Split(Char[])

串联对象数组的各个元素，其中在每个元素之间使用指定的分隔符。Concatenates the elements of an object array, using the specified separator between each element.

public:
 static System::String ^ Join(System::String ^ separator, ... cli::array <System::Object ^> ^ values);

[System.Runtime.InteropServices.ComVisible(false)]
public static string Join (string separator, params object[] values);

static member Join : string * obj[] -> string

Public Shared Function Join (separator As String, ParamArray values As Object()) As String

参数

返回

属性

ComVisibleAttribute

异常

示例

下面的示例使用埃拉托色 of 尼斯筛法算法来计算小于或等于100的质数。The following example uses the Sieve of Eratosthenes algorithm to calculate the prime numbers that are less than or equal to 100. 它将结果分配给一个整数数组，然后将结果传递给 Join(String, Object[]) 方法。It assigns the result to a integer array, which it then passes to the Join(String, Object[]) method.

using System;
using System.Collections.Generic;

public class Example
{
   public static void Main()
   {
      int maxPrime = 100;
      int[] primes = GetPrimes(maxPrime);
      Console.WriteLine("Primes less than {0}:", maxPrime);
      Console.WriteLine("   {0}", String.Join(" ", primes));
   }

   private static int[] GetPrimes(int maxPrime)
   {
      Array values = Array.CreateInstance(typeof(int), 
                              new int[] { maxPrime - 1}, new int[] { 2 }); 
      // Use Sieve of Eratosthenes to determine prime numbers.
      for (int ctr = values.GetLowerBound(0); ctr <= (int) Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))); ctr++)
      {
                           
         if ((int) values.GetValue(ctr) == 1) continue;
         
         for (int multiplier = ctr; multiplier <=  maxPrime / 2; multiplier++)
            if (ctr * multiplier <= maxPrime)
               values.SetValue(1, ctr * multiplier);
      }      
      
      List<int> primes = new List<int>();
      for (int ctr = values.GetLowerBound(0); ctr <= values.GetUpperBound(0); ctr++)
         if ((int) values.GetValue(ctr) == 0) 
            primes.Add(ctr);
      return primes.ToArray();
   }   
}
// The example displays the following output:
//    Primes less than 100:
//       2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Module Example
   Public Sub Main()
      Dim maxPrime As Integer = 100
      Dim primes() As Integer = GetPrimes(maxPrime)
      Console.WriteLine("Primes less than {0}:", maxPrime)
      Console.WriteLine("   {0}", String.Join(" ", primes))
   End Sub
   
   Private Function GetPrimes(maxPrime As Integer) As Integer()
      Dim values As Array = Array.CreateInstance(GetType(Integer), _
                              New Integer() { maxPrime - 1}, New Integer(){ 2 }) 
        ' Use Sieve of Eratosthenes to determine prime numbers.
      For ctr As Integer = values.GetLowerBound(0) To _
                           CInt(Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))))
         If CInt(values.GetValue(ctr)) = 1 Then Continue For
         
         For multiplier As Integer = ctr To maxPrime \ 2
            If ctr * multiplier <= maxPrime Then values.SetValue(1, ctr * multiplier)
         Next   
      Next      
      
      Dim primes As New System.Collections.Generic.List(Of Integer)
      For ctr As Integer = values.GetLowerBound(0) To values.GetUpperBound(0)
         If CInt(values.GetValue(ctr)) = 0 Then primes.Add(ctr)
      Next            
      Return primes.ToArray()
   End Function   
End Module
' The example displays the following output:
'    Primes less than 100:
'       2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

注解

如果 separator null 或者第一个元素 values 之外的任何元素 null，则改用空字符串（String.Empty）。If separator is null or if any element of values other than the first element is null, an empty string (String.Empty) is used instead. 如果 null``values 的第一个元素，请参阅 "调用方的说明" 部分。See the Notes for Callers section if the first element of values is null.

Join(String, Object[]) 是一种简便方法，可让你连接对象数组中的每个元素，而无需将其元素显式转换为字符串。Join(String, Object[]) is a convenience method that lets you concatenate each element in an object array without explicitly converting its elements to strings. 数组中每个对象的字符串表示形式都是通过调用该对象的 ToString 方法派生的。The string representation of each object in the array is derived by calling that object's ToString method.

调用方说明

如果 nullvalues 的第一个元素，则 Join(String, Object[]) 方法不会连接 values 中的元素，而是返回 Empty。If the first element of values is null, the Join(String, Object[]) method does not concatenate the elements in values but instead returns Empty. 此问题有多种解决方法。A number of workarounds for this issue are available. 最简单的方法是将 Empty 的值分配给数组的第一个元素，如下面的示例所示。The easiest is to assign a value of Empty to the first element of the array, as the following example shows.

[!code-csharpSystem.String.Join#6] [!code-vbSystem.String.Join#6][!code-csharpSystem.String.Join#6] [!code-vbSystem.String.Join#6]

另请参阅

• Split(Char[])

串联字符串数组的所有元素，其中在每个元素之间使用指定的分隔符。Concatenates all the elements of a string array, using the specified separator between each element.

public:
 static System::String ^ Join(System::String ^ separator, cli::array <System::String ^> ^ value);

public static string Join (string separator, string[] value);

static member Join : string * string[] -> string

Public Shared Function Join (separator As String, value As String()) As String

参数

返回

异常

示例

下面的示例演示 Join 方法。The following example demonstrates the Join method.

using namespace System;
String^ MakeLine( int initVal, int multVal, String^ sep )
{
   array<String^>^sArr = gcnew array<String^>(10);
   for ( int i = initVal; i < initVal + 10; i++ )
      sArr[ i - initVal ] = String::Format( "{0, -3}", i * multVal );
   return String::Join( sep, sArr );
}

int main()
{
   Console::WriteLine( MakeLine( 0, 5, ", " ) );
   Console::WriteLine( MakeLine( 1, 6, "  " ) );
   Console::WriteLine( MakeLine( 9, 9, ": " ) );
   Console::WriteLine( MakeLine( 4, 7, "< " ) );
}
// The example displays the following output:
//       0  , 5  , 10 , 15 , 20 , 25 , 30 , 35 , 40 , 45
//       6    12   18   24   30   36   42   48   54   60
//       81 : 90 : 99 : 108: 117: 126: 135: 144: 153: 162
//       28 < 35 < 42 < 49 < 56 < 63 < 70 < 77 < 84 < 91

using System;

public class JoinTest 
{
    public static void Main() 
    {
        Console.WriteLine(MakeLine(0, 5, ", "));
        Console.WriteLine(MakeLine(1, 6, "  "));
        Console.WriteLine(MakeLine(9, 9, ": "));
        Console.WriteLine(MakeLine(4, 7, "< "));
    }

    private static string MakeLine(int initVal, int multVal, string sep) 
    {
        string [] sArr = new string [10];

        for (int i = initVal; i < initVal + 10; i++)
            sArr[i - initVal] = String.Format("{0,-3}", i * multVal);

        return String.Join(sep, sArr);
    }
}
// The example displays the following output:
//       0  , 5  , 10 , 15 , 20 , 25 , 30 , 35 , 40 , 45
//       6    12   18   24   30   36   42   48   54   60
//       81 : 90 : 99 : 108: 117: 126: 135: 144: 153: 162
//       28 < 35 < 42 < 49 < 56 < 63 < 70 < 77 < 84 < 91  

Public Class JoinTest
    
    Public Shared Sub Main()
        
        Console.WriteLine(MakeLine(0, 5, ", "))
        Console.WriteLine(MakeLine(1, 6, "  "))
        Console.WriteLine(MakeLine(9, 9, ": "))
        Console.WriteLine(MakeLine(4, 7, "< "))
    End Sub
    
    
    Private Shared Function MakeLine(initVal As Integer, multVal As Integer, sep As String) As String
        Dim sArr(10) As String
        Dim i As Integer
        
        
        For i = initVal To (initVal + 10) - 1
            sArr((i - initVal)) = [String].Format("{0,-3}", i * multVal)
        
        Next i
        Return [String].Join(sep, sArr)
    End Function 'MakeLine
End Class
' The example displays the following output:
'       0  , 5  , 10 , 15 , 20 , 25 , 30 , 35 , 40 , 45
'       6    12   18   24   30   36   42   48   54   60
'       81 : 90 : 99 : 108: 117: 126: 135: 144: 153: 162
'       28 < 35 < 42 < 49 < 56 < 63 < 70 < 77 < 84 < 91

注解

例如，如果 separator 为 "，" 并且 value 的元素为 "apple"、"橙色"、"grape" 和 "梨"，Join(separator, value) 将返回 "apple，橙色，grape，梨"。For example, if separator is ", " and the elements of value are "apple", "orange", "grape", and "pear", Join(separator, value) returns "apple, orange, grape, pear".

如果 null``separator，则改为使用空字符串（String.Empty）。If separator is null, an empty string (String.Empty) is used instead. 如果 null``value 中的任何元素，则改为使用空字符串。If any element in value is null, an empty string is used instead.

另请参阅

• Concat(Object)

连接字符串数组，其中在每个成员之间使用指定的分隔符，并且从位于 startIndex 位置的 value 中的元素开始，并连接多达 count 个元素。Concatenates an array of strings, using the specified separator between each member, starting with the element in value located at the startIndex position, and concatenating up to count elements.

public:
 static System::String ^ Join(char separator, cli::array <System::String ^> ^ value, int startIndex, int count);

public static string Join (char separator, string[] value, int startIndex, int count);

static member Join : char * string[] * int * int -> string

Public Shared Function Join (separator As Char, value As String(), startIndex As Integer, count As Integer) As String

参数

返回

异常

串联字符串数组的指定元素，其中在每个元素之间使用指定的分隔符。Concatenates the specified elements of a string array, using the specified separator between each element.

public:
 static System::String ^ Join(System::String ^ separator, cli::array <System::String ^> ^ value, int startIndex, int count);

public static string Join (string separator, string[] value, int startIndex, int count);

static member Join : string * string[] * int * int -> string

Public Shared Function Join (separator As String, value As String(), startIndex As Integer, count As Integer) As String

参数

返回

异常

示例

下面的示例连接水果名称数组中的两个元素。The following example concatenates two elements from an array of names of fruit.

// Sample for String::Join(String, String[], int int)
using namespace System;
int main()
{
   array<String^>^val = {"apple","orange","grape","pear"};
   String^ sep = ", ";
   String^ result;
   Console::WriteLine( "sep = '{0}'", sep );
   Console::WriteLine( "val[] = {{'{0}' '{1}' '{2}' '{3}'}}", val[ 0 ], val[ 1 ], val[ 2 ], val[ 3 ] );
   result = String::Join( sep, val, 1, 2 );
   Console::WriteLine( "String::Join(sep, val, 1, 2) = '{0}'", result );
}

/*
This example produces the following results:
sep = ', '
val[] = {'apple' 'orange' 'grape' 'pear'}
String::Join(sep, val, 1, 2) = 'orange, grape'
*/

String[] val = {"apple", "orange", "grape", "pear"};
String sep   = ", ";
String result;

Console.WriteLine("sep = '{0}'", sep);
Console.WriteLine("val[] = {{'{0}' '{1}' '{2}' '{3}'}}", val[0], val[1], val[2], val[3]);
result = String.Join(sep, val, 1, 2);
Console.WriteLine("String.Join(sep, val, 1, 2) = '{0}'", result);

// This example produces the following results:
// sep = ', '
// val[] = {'apple' 'orange' 'grape' 'pear'}
// String.Join(sep, val, 1, 2) = 'orange, grape'

Class Sample
   Public Shared Sub Main()
      Dim val As [String]() =  {"apple", "orange", "grape", "pear"}
      Dim sep As [String] = ", "
      Dim result As [String]
      
      Console.WriteLine("sep = '{0}'", sep)
      Console.WriteLine("val() = {{'{0}' '{1}' '{2}' '{3}'}}", val(0), val(1), val(2), val(3))
      result = [String].Join(sep, val, 1, 2)
      Console.WriteLine("String.Join(sep, val, 1, 2) = '{0}'", result)
   End Sub
End Class 
'This example displays the following output:
'       sep = ', '
'       val() = {'apple' 'orange' 'grape' 'pear'}
'       String.Join(sep, val, 1, 2) = 'orange, grape'

注解

例如，如果 separator 为 "，" 且 value 的元素为 "apple"、"橙色"、"grape" 和 "梨"，Join(separator, value, 1, 2) 将返回 "橙色，grape"。For example, if separator is ", " and the elements of value are "apple", "orange", "grape", and "pear", Join(separator, value, 1, 2) returns "orange, grape".

如果 null``separator，则改为使用空字符串（String.Empty）。If separator is null, an empty string (String.Empty) is used instead. 如果 null``value 中的任何元素，则改为使用空字符串。If any element in value is null, an empty string is used instead.

另请参阅

• Split(Char[])

串联集合的成员，其中在每个成员之间使用指定的分隔符。Concatenates the members of a collection, using the specified separator between each member.

public:
generic <typename T>
 static System::String ^ Join(char separator, System::Collections::Generic::IEnumerable<T> ^ values);

public static string Join<T> (char separator, System.Collections.Generic.IEnumerable<T> values);

static member Join : char * seq<'T> -> string

Public Shared Function Join(Of T) (separator As Char, values As IEnumerable(Of T)) As String

类型参数

参数

返回

异常

串联集合的成员，其中在每个成员之间使用指定的分隔符。Concatenates the members of a collection, using the specified separator between each member.

public:
generic <typename T>
 static System::String ^ Join(System::String ^ separator, System::Collections::Generic::IEnumerable<T> ^ values);

[System.Runtime.InteropServices.ComVisible(false)]
public static string Join<T> (string separator, System.Collections.Generic.IEnumerable<T> values);

static member Join : string * seq<'T> -> string

Public Shared Function Join(Of T) (separator As String, values As IEnumerable(Of T)) As String

类型参数

参数

返回

属性

ComVisibleAttribute

异常

示例

下面的示例使用埃拉托色 of 尼斯筛法算法来计算小于或等于100的质数。The following example uses the Sieve of Eratosthenes algorithm to calculate the prime numbers that are less than or equal to 100. 它将结果分配给类型为 integer 的 List<T> 对象，然后将其传递给 Join<T>(String, IEnumerable<T>) 方法。It assigns the result to a List<T> object of type integer, which it then passes to the Join<T>(String, IEnumerable<T>) method.

using System;
using System.Collections.Generic;

public class Example
{
   public static void Main()
   {
      int maxPrime = 100;
      List<int> primes = GetPrimes(maxPrime);
      Console.WriteLine("Primes less than {0}:", maxPrime);
      Console.WriteLine("   {0}", String.Join(" ", primes));
   }

   private static List<int> GetPrimes(int maxPrime)
   {
      Array values = Array.CreateInstance(typeof(int), 
                              new int[] { maxPrime - 1}, new int[] { 2 });
      // Use Sieve of Eratosthenes to determine prime numbers.
      for (int ctr = values.GetLowerBound(0); ctr <= (int) Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))); ctr++)
      {
                           
         if ((int) values.GetValue(ctr) == 1) continue;
         
         for (int multiplier = ctr; multiplier <=  maxPrime / 2; multiplier++)
            if (ctr * multiplier <= maxPrime)
               values.SetValue(1, ctr * multiplier);
      }      
      
      List<int> primes = new List<int>();
      for (int ctr = values.GetLowerBound(0); ctr <= values.GetUpperBound(0); ctr++)
         if ((int) values.GetValue(ctr) == 0) 
            primes.Add(ctr);
      return primes;
   }   
}
// The example displays the following output:
//    Primes less than 100:
//       2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Imports System.Collections.Generic

Module Example
   Public Sub Main()
      Dim maxPrime As Integer = 100
      Dim primes As List(Of Integer) = GetPrimes(maxPrime)
      Console.WriteLine("Primes less than {0}:", maxPrime)
      Console.WriteLine("   {0}", String.Join(" ", primes))
   End Sub
   
   Private Function GetPrimes(maxPrime As Integer) As List(Of Integer)
      Dim values As Array = Array.CreateInstance(GetType(Integer), _
                              New Integer() { maxPrime - 1}, New Integer(){ 2 }) 
        ' Use Sieve of Eratosthenes to determine prime numbers.
      For ctr As Integer = values.GetLowerBound(0) To _
                           CInt(Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))))
         If CInt(values.GetValue(ctr)) = 1 Then Continue For
         
         For multiplier As Integer = ctr To maxPrime \ 2
            If ctr * multiplier <= maxPrime Then values.SetValue(1, ctr * multiplier)
         Next   
      Next      
      
      Dim primes As New System.Collections.Generic.List(Of Integer)
      For ctr As Integer = values.GetLowerBound(0) To values.GetUpperBound(0)
         If CInt(values.GetValue(ctr)) = 0 Then primes.Add(ctr)
      Next            
      Return primes
   End Function   
End Module
' The example displays the following output:
'    Primes less than 100:
'       2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

注解

如果 null``separator，则改为使用空字符串（String.Empty）。If separator is null, an empty string (String.Empty) is used instead. 如果 null``values 的任何成员，则改为使用空字符串。If any member of values is null, an empty string is used instead.

Join<T>(String, IEnumerable<T>) 是一种简便方法，使你可以连接 IEnumerable<T> 集合的每个成员，无需先将其转换为字符串。Join<T>(String, IEnumerable<T>) is a convenience method that lets you concatenate each member of an IEnumerable<T> collection without first converting them to strings. IEnumerable<T> 集合中每个对象的字符串表示形式是通过调用该对象的 ToString 方法派生的。The string representation of each object in the IEnumerable<T> collection is derived by calling that object's ToString method.

此方法对语言集成查询（LINQ）查询表达式特别有用。This method is particular useful with Language-Integrated Query (LINQ) query expressions. 例如，下面的代码定义了一个非常简单的 Animal 类，该类包含动物的名称以及其所属的顺序。For example, the following code defines a very simple Animal class that contains the name of an animal and the order to which it belongs. 然后，它定义包含多个 Animal 对象的 List<T> 对象。It then defines a List<T> object that contains a number of Animal objects. 调用 Enumerable.Where 扩展方法以提取其 Order 属性等于 "啮齿类" 的 Animal 对象。The Enumerable.Where extension method is called to extract the Animal objects whose Order property equals "Rodent". 结果传递给 Join<T>(String, IEnumerable<T>) 方法。The result is passed to the Join<T>(String, IEnumerable<T>) method.

using System;
using System.Collections.Generic;
using System.Linq;

public class Animal
{
   public string Kind;
   public string Order;
   
   public Animal(string kind, string order)
   {
      this.Kind = kind;
      this.Order = order;
   }
   
   public override string ToString()
   {
      return this.Kind;
   }
}

public class Example
{
   public static void Main()
   {
      List<Animal> animals = new List<Animal>();
      animals.Add(new Animal("Squirrel", "Rodent"));
      animals.Add(new Animal("Gray Wolf", "Carnivora"));
      animals.Add(new Animal("Capybara", "Rodent"));
      string output = String.Join(" ", animals.Where( animal => 
                      (animal.Order == "Rodent")));
      Console.WriteLine(output);  
   }
}
// The example displays the following output:
//      Squirrel Capybara

Imports System.Collections.Generic

Public Class Animal
   Public Kind As String
   Public Order As String
   
   Public Sub New(kind As String, order As String)
      Me.Kind = kind
      Me.Order = order
   End Sub
   
   Public Overrides Function ToString() As String
      Return Me.Kind
   End Function
End Class

Module Example
   Public Sub Main()
      Dim animals As New List(Of Animal)
      animals.Add(New Animal("Squirrel", "Rodent"))
      animals.Add(New Animal("Gray Wolf", "Carnivora"))
      animals.Add(New Animal("Capybara", "Rodent")) 
      Dim output As String = String.Join(" ", animals.Where(Function(animal) _
                                           animal.Order = "Rodent"))
      Console.WriteLine(output)                                           
   End Sub
End Module
' The example displays the following output:
'      Squirrel Capybara

另请参阅

• Split(Char[])