String.Join 方法

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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

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

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

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

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

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

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

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

參數

傳回

由 separator 字串分隔之 value 中的專案所組成的字串。

-或-

如果 value 有零個專案，Empty。

例外狀況

範例

下列範例示範 Join 方法。

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

open System

let makeLine initVal multVal (sep: string) =
    let sArr = Array.zeroCreate<string> 10 

    for i = initVal to initVal + 9 do
        sArr[i - initVal] <- String.Format("{0,-3}", i * multVal)

    String.Join(sep, sArr)

printfn $"""{makeLine 0 5 ", "}"""
printfn $"""{makeLine 1 6 "  "}"""
printfn $"""{makeLine 9 9 ": "}"""
printfn $"""{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

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

備註

例如，如果 separator 為 “， 且 value 的元素為 ”apple“、”orange“、”grape“ 和 ”pear“，Join(separator, value) 會傳回 ”apple、orange、grape、pear“。

如果 separator 是 null，則會改用空字串 （String.Empty）。 如果 value 中的任何專案 null，則會改用空字串。

另請參閱

• Concat(Object)

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

public static string Join (string? separator, scoped ReadOnlySpan<string?> value);

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

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

參數

傳回

由 separator 字串分隔之 value 專案的字串。 -或- 如果 value 有零個元素，則為 -或- Empty。

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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);

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

參數

傳回

字串，由 value 的 count 專案所組成，從以 separator 字元分隔的 startIndex 開始。

-或-

如果 count 為零，Empty。

例外狀況

範例

下列範例會串連水果名稱陣列中的兩個元素。

// 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'

open System

let vals = [| "apple"; "orange"; "grape"; "pear" |]
let sep   = ", "

printfn $"sep = '{sep}'"
printfn $"vals[] = {{'{vals[0]}' '{vals[1]}' '{vals[2]}' '{vals[3]}'}}"
let result = String.Join(sep, vals, 1, 2)
printfn $"String.Join(sep, vals, 1, 2) = '{result}'"

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

備註

例如，如果 separator 為 “， 且 value 的元素為 ”apple“、”orange“、”grape“ 和 ”pear“，Join(separator, value, 1, 2) 會傳回 ”orange， grape“。

如果 separator 是 null，則會改用空字串 （String.Empty）。 如果 value 中的任何專案 null，則會改用空字串。

另請參閱

• Split(Char[])

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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);

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

參數

傳回

字串，由 value 的 count 專案所組成，從以 separator 字元分隔的 startIndex 開始。

-或-

如果 count 為零，Empty。

例外狀況

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

public static string Join (string? separator, scoped ReadOnlySpan<object?> values);

static member Join : string * ReadOnlySpan<obj> -> string

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

參數

傳回

由 separator 字串分隔之 values 專案的字串。 -或- 如果 values 有零個元素，則為 -或- Empty。

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

public static string Join (char separator, scoped ReadOnlySpan<object?> values);

static member Join : char * ReadOnlySpan<obj> -> string

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

參數

傳回

字串，由 separator 字元分隔的 values 項目所組成。 -或- 如果 values 有零個元素，則為 -或- Empty。

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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

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

public static string Join (string? separator, System.Collections.Generic.IEnumerable<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

[<System.Runtime.InteropServices.ComVisible(false)>]
static member Join : string * seq<string> -> string

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

參數

傳回

由 separator 字串分隔之 values 專案的字串。

-或-

如果 values 有零個專案，Empty。

屬性

ComVisibleAttribute

例外狀況

範例

下列範例會使用 Eratosthenes 演算法的 Sieve 來計算小於或等於 100 的質數。 它會將結果指派給類型為 StringList<T> 對象，然後傳遞給 Join(String, IEnumerable<String>) 方法。

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

open System

let getPrimes maxPrime =
    let values = Array.CreateInstance(typeof<int>, [| maxPrime - 1 |], [| 2 |])
    // Use Sieve of Eratosthenes to determine prime numbers.
    for i = values.GetLowerBound 0 to values.GetUpperBound 0 |> float |> sqrt |> ceil |> int do
        if values.GetValue i :?> int <> 1 then
            for multiplier = i to maxPrime / 2 do
                if i * multiplier <= maxPrime then
                    values.SetValue(1, i * multiplier)

    let primes = ResizeArray()
    for i = values.GetLowerBound 0 to values.GetUpperBound 0 do
        if values.GetValue i :?> int = 0 then
            primes.Add i
    primes

let maxPrime = 100
let primes = getPrimes maxPrime
printfn $"Primes less than {maxPrime}:"
printfn $"""   {String.Join(" ", 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

備註

如果 separator 是 null，則會改用空字串 （String.Empty）。 如果 values 的任何成員 null，則會改用空字串。

Join(String, IEnumerable<String>) 是一種方便的方法，可讓您串連 IEnumerable(Of String) 集合中的每個專案，而不需要先將項目轉換成字串陣列。 它特別適用於 Language-Integrated Query （LINQ） 查詢表達式。 下列範例會將包含字母大寫或小寫字母的 List(Of String) 對象傳遞至 Lambda 運算式，該表達式會選取等於或大於特定字母的字母（在此範例中為 “M” ）。 Enumerable.Where 方法傳回的 IEnumerable(Of String) 集合會傳遞至 Join(String, IEnumerable<String>) 方法，以將結果顯示為單一字串。

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(((char)(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

// This F# example uses Seq.filter instead of Linq.
open System

let getAlphabet upper =
    let charValue = if upper then 65 else 97
    seq {
        for i = 0 to 25 do
            charValue + i
            |> char
            |> string
    }

String.Join(" ", getAlphabet true |> Seq.filter (fun letter -> letter.CompareTo "M" >= 0))
|> printfn "%s"

// 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

另請參閱

• Split(Char[])

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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

public static string Join (char separator, params 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

參數

傳回

字串，由 separator 字元分隔的 values 項目所組成。

-或-

如果 values 有零個專案，Empty。

例外狀況

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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

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

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

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

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

[<System.Runtime.InteropServices.ComVisible(false)>]
static member Join : string * obj[] -> string

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

參數

傳回

由 separator 字串分隔之 values 專案的字串。

-或-

如果 values 有零個專案，Empty。

-或-

僅限 .NET Framework：如果 values 的第一個專案 null，Empty 。

屬性

ComVisibleAttribute

例外狀況

範例

下列範例會使用 Eratosthenes 演算法的 Sieve 來計算小於或等於 100 的質數。 它會將結果指派給整數數位，然後傳遞給 Join(String, Object[]) 方法。

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

open System

let getPrimes maxPrime =
    let values = Array.CreateInstance(typeof<int>, [| maxPrime - 1 |], [| 2 |])
    // Use Sieve of Eratosthenes to determine prime numbers.
    for i = values.GetLowerBound 0 to values.GetUpperBound 0 |> float |> sqrt |> ceil |> int do
        if values.GetValue i :?> int <> 1 then
            for multiplier = i to maxPrime / 2 do
                if i * multiplier <= maxPrime then
                    values.SetValue(1, i * multiplier)

    [| for i = values.GetLowerBound 0 to values.GetUpperBound 0 do
        if values.GetValue i :?> int = 0 then
            i |]

let maxPrime = 100
let primes = getPrimes maxPrime
printfn $"Primes less than {maxPrime}:"
printfn $"""   {String.Join(" ", 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

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

備註

如果 separator 是 null，或者如果第一個元素以外的任何 values 專案 null，則會改用空字串 （String.Empty）。 如果 values 的第一個專案 null，請參閱呼叫端注意事項一節。

Join(String, Object[]) 是一種便利的方法，可讓您串連物件陣列中的每個元素，而不需要將其元素明確轉換成字串。 數位中每個物件的字串表示都是藉由呼叫該物件的 ToString 方法來衍生。

給呼叫者的注意事項

僅限 .NET Framework：如果 values 的第一個專案是 null，則 Join(String, Object[]) 方法不會串連 values 中的專案，而是傳回 Empty。 有一些此問題的因應措施可供使用。 最簡單的方法是將 Empty 值指派給陣列的第一個專案，如下列範例所示。

object[] values = { null, "Cobb", 4189, 11434, .366 };
if (values[0] == null) values[0] = String.Empty;
Console.WriteLine(String.Join("|", values));

// The example displays the following output:
//      |Cobb|4189|11434|0.366

let values: obj[] = [| null; "Cobb"; 4189; 11434; 0.366 |]
if values[0] = null then 
   values[0] <- String.Empty
printfn $"""{String.Join("|", values)}"""

// The example displays the following output:
//      |Cobb|4189|11434|0.366

Dim values() As Object = { Nothing, "Cobb", 4189, 11434, .366 }
If values(0) Is Nothing Then values(0) = String.Empty
Console.WriteLine(String.Join("|", values))
' The example displays the following output:
'      |Cobb|4189|11434|0.366

另請參閱

• Split(Char[])

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

public static string Join (char separator, scoped ReadOnlySpan<string?> value);

static member Join : char * ReadOnlySpan<string> -> string

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

參數

傳回

由 separator 字串分隔之 value 專案的字串。 -或- 如果 value 有零個元素，則為 -或- Empty。

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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

public static string Join (char separator, params 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

參數

傳回

字串，由 separator 字元分隔的 value 項目所組成。

-或-

如果 value 有零個專案，Empty。

例外狀況

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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

類型參數

參數

傳回

由 separator 字元分隔之 values 成員組成的字串。

-或-

如果 values 沒有專案，Empty。

例外狀況

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

來源:

String.Manipulation.cs

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

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

public static string Join<T> (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

[<System.Runtime.InteropServices.ComVisible(false)>]
static member Join : string * seq<'T> -> string

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

類型參數

參數

傳回

由 separator 字串分隔之 values 專案的字串。

-或-

如果 values 沒有專案，Empty。

屬性

ComVisibleAttribute

例外狀況

範例

下列範例會使用 Eratosthenes 演算法的 Sieve 來計算小於或等於 100 的質數。 它會將結果指派給整數類型的 List<T> 對象，然後傳遞給 Join<T>(String, IEnumerable<T>) 方法。

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

open System

let getPrimes maxPrime =
    let values = Array.CreateInstance(typeof<int>, [| maxPrime - 1 |], [| 2 |])
    // Use Sieve of Eratosthenes to determine prime numbers.
    for i = values.GetLowerBound 0 to values.GetUpperBound 0 |> float |> sqrt |> ceil |> int do
        if values.GetValue i <> 1 then
            for multiplier = i to maxPrime / 2 do
                if i * multiplier <= maxPrime then
                    values.SetValue(1, i * multiplier)

    let primes = ResizeArray()
    for i = values.GetLowerBound 0 to values.GetUpperBound 0 do
        if values.GetValue i :?> int = 0 then
            primes.Add i
    primes

let maxPrime = 100
let primes = getPrimes maxPrime
printfn $"Primes less than {maxPrime}:"
printfn $"""   {String.Join(" ", 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

備註

如果 separator 是 null，則會改用空字串 （String.Empty）。 如果 values 的任何成員 null，則會改用空字串。

Join<T>(String, IEnumerable<T>) 是一種方便的方法，可讓您串連 IEnumerable<T> 集合的每個成員，而不需要先將它們轉換成字串。 IEnumerable<T> 集合中每個物件的字串表示，是藉由呼叫該物件的 ToString 方法來衍生。

此方法特別適用於 Language-Integrated Query （LINQ） 查詢表示式。 例如，下列程式代碼會定義非常簡單的 Animal 類別，其中包含動物的名稱及其所屬的順序。 然後，它會定義包含數個 Animal 物件的 List<T> 物件。 呼叫 Enumerable.Where 擴充方法，以擷取 Order 屬性等於 “Rodent” 的 Animal 物件。 結果會傳遞至 Join<T>(String, IEnumerable<T>) 方法。

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

// This example uses F#'s Seq.filter function instead of Linq.
open System

type Animal =
  { Kind: string
    Order: string }
    override this.ToString() =
        this.Kind

let animals = ResizeArray()
animals.Add { Kind = "Squirrel"; Order = "Rodent" }
animals.Add { Kind = "Gray Wolf"; Order = "Carnivora" }
animals.Add { Kind = "Capybara"; Order = "Rodent" }
String.Join(" ", animals |> Seq.filter (fun animal -> animal.Order = "Rodent"))
|> printfn "%s"
// 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

另請參閱

• Split(Char[])