String.Join 方法
定义
连接指定数组的元素或集合的成员,在每个元素或成员之间使用指定的分隔符。Concatenates the elements of a specified array or the members of a collection, using the specified separator between each element or member.
重载
Join(Char, Object[]) |
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. |
Join(Char, String[]) |
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. |
Join(String, IEnumerable<String>) |
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. |
Join(String, Object[]) |
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. |
Join(String, String[]) |
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. |
Join(Char, String[], Int32, Int32) |
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 |
Join(String, String[], Int32, Int32) |
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. |
Join<T>(Char, IEnumerable<T>) |
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. |
Join<T>(String, IEnumerable<T>) |
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. |
Join(Char, Object[])
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
- separator
- Char
要用作分隔符的字符。The character to use as a separator. 只有在 separator
具有多个元素时,value
才包括在返回的字符串中。separator
is included in the returned string only if value
has more than one element.
- values
- Object[]
将连接其字符串表示形式的对象数组。An array of objects whose string representations will be concatenated.
返回
一个由 values
的元素组成的字符串,这些元素以 separator
字符分隔。A string that consists of the elements of values
delimited by the separator
character.
或-or-
如果 values
包含零个元素或 values
的所有元素都为 null
,则为 Empty。Empty if values
has zero elements or all the elements of values
are null
.
异常
value
为 null
。value
is null
.
Join(Char, String[])
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
- separator
- Char
要用作分隔符的字符。The character to use as a separator. 只有在 separator
具有多个元素时,value
才包括在返回的字符串中。separator
is included in the returned string only if value
has more than one element.
- value
- String[]
要连接的字符串数组。An array of strings to concatenate.
返回
一个由 value
的元素组成的字符串,这些元素以 separator
字符分隔。A string that consists of the elements of value
delimited by the separator
character.
或-or-
如果 value
包含零个元素或 value
的所有元素都为 null
,则为 Empty。Empty if value
has zero elements or all the elements of value
are null
.
异常
value
为 null
。value
is null
.
Join(String, IEnumerable<String>)
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
- separator
- String
要用作分隔符的字符串。separator
The string to use as a separator.separator
包括在返回的字符串中(只有在 values
具有多个元素时)。is included in the returned string only if values
has more than one element.
- values
- IEnumerable<String>
一个包含要串联的字符串的集合。A collection that contains the strings to concatenate.
返回
一个由 values
的成员组成的字符串,这些成员以 separator
字符串分隔。A string that consists of the members of values
delimited by the separator
string.
或-or-
如果 values
包含零个元素或 values
的所有元素都为 null
,则为 Empty。Empty if values
has zero elements or all the elements of values
are null
.
- 属性
异常
values
为 null
。values
is null
.
生成的字符串长度超出了允许的最大长度 (MaxValue)。The length of the resulting string overflows the maximum allowed length (MaxValue).
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
Join(String, Object[])
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
- separator
- String
要用作分隔符的字符串。The string to use as a separator. 只有在 separator
具有多个元素时,values
才包括在返回的字符串中。separator
is included in the returned string only if values
has more than one element.
- values
- Object[]
一个数组,其中包含要连接的元素。An array that contains the elements to concatenate.
返回
一个由 values
的元素组成的字符串,这些元素以 separator
字符串分隔。A string that consists of the elements of values
delimited by the separator
string. 如果 values
为空数组,该方法将返回 Empty。If values
is an empty array, the method returns Empty.
- 属性
异常
values
为 null
。values
is null
.
生成的字符串长度超出了允许的最大长度 (MaxValue)。The length of the resulting string overflows the maximum allowed length (MaxValue).
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 null
values
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
Join(String, String[])
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
- separator
- String
要用作分隔符的字符串。The string to use as a separator. 只有在 separator
具有多个元素时,value
才包括在返回的字符串中。separator
is included in the returned string only if value
has more than one element.
- value
- String[]
一个数组,其中包含要连接的元素。An array that contains the elements to concatenate.
返回
一个由 value
中的元素组成的字符串,这些元素以 separator
字符串分隔。A string that consists of the elements in value
delimited by the separator
string. 如果 value
为空数组,该方法将返回 Empty。If value
is an empty array, the method returns Empty.
异常
value
为 null
。value
is null
.
生成的字符串长度超出了允许的最大长度 (MaxValue)。The length of the resulting string overflows the maximum allowed length (MaxValue).
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
Join(Char, String[], Int32, Int32)
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
- separator
- Char
连接字符串数组,其中在每个成员之间使用指定的分隔符,并且从位于指定索引处的元素开始,并包含指定数量的元素。Concatenates an array of strings, using the specified separator between each member, starting with the element located at the specified index and including a specified number of elements.
- value
- String[]
要连接的字符串数组。An array of strings to concatenate.
- startIndex
- Int32
要连接的 value
中的第一个项。The first item in value
to concatenate.
- count
- Int32
要连接的 value
中的元素数,从位于 startIndex
位置的元素开始。The number of elements from value
to concatenate, starting with the element in the startIndex
position.
返回
一个由 value
的元素组成的字符串,这些元素以 separator
字符分隔。A string that consists of the elements of value
delimited by the separator
character.
或-or-
如果 count
为零,value
没有元素,或 value
的全部元素均为 null
或 Empty,则为 Empty。Empty if count
is zero, value
has no elements, or all the elements of value
are null
or Empty.
异常
value
为 null
。value
is null
.
startIndex
或 count
为负。startIndex
or count
are negative.
或-or-
startIndex
大于 value
的长度 - count
。startIndex
is greater than the length of value
- count
.
Join(String, String[], Int32, Int32)
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
- separator
- String
要用作分隔符的字符串。The string to use as a separator. 只有在 separator
具有多个元素时,value
才包括在返回的字符串中。separator
is included in the returned string only if value
has more than one element.
- value
- String[]
一个数组,其中包含要连接的元素。An array that contains the elements to concatenate.
- startIndex
- Int32
value
中要使用的第一个元素。The first element in value
to use.
- count
- Int32
要使用的 value
的元素数。The number of elements of value
to use.
返回
由 value
中的字符串组成的字符串,这些字符串以 separator
字符串分隔。A string that consists of the strings in value
delimited by the separator
string.
或-or-
如果 Empty 为零,count
没有元素,或 value
以及 separator
的全部元素均为 value
,则为 Empty。Empty if count
is zero, value
has no elements, or separator
and all the elements of value
are Empty.
异常
value
为 null
。value
is null
.
startIndex
或 count
小于 0。startIndex
or count
is less than 0.
或-or-
startIndex
加上 count
大于 value
中的元素数。startIndex
plus count
is greater than the number of elements in value
.
内存不足。Out of memory.
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
Join<T>(Char, IEnumerable<T>)
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
- T
values
成员的类型。The type of the members of values
.
参数
- separator
- Char
要用作分隔符的字符。The character to use as a separator. 只有在 separator
具有多个元素时,values
才包括在返回的字符串中。separator
is included in the returned string only if values
has more than one element.
- values
- IEnumerable<T>
一个包含要串联的对象的集合。A collection that contains the objects to concatenate.
返回
一个由 values
的成员组成的字符串,这些成员以 separator
字符分隔。A string that consists of the members of values
delimited by the separator
character. 如果 values
没有成员,则该方法返回 Empty。If values
has no members, the method returns Empty.
异常
values
为 null
。values
is null
.
Join<T>(String, IEnumerable<T>)
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
- T
values
成员的类型。The type of the members of values
.
参数
- separator
- String
要用作分隔符的字符串。The string to use as a separator. 只有在 separator
具有多个元素时,values
才包括在返回的字符串中。separator
is included in the returned string only if values
has more than one element.
- values
- IEnumerable<T>
一个包含要串联的对象的集合。A collection that contains the objects to concatenate.
返回
一个由 values
的成员组成的字符串,这些成员以 separator
字符串分隔。A string that consists of the members of values
delimited by the separator
string. 如果 values
没有成员,则该方法返回 Empty。If values
has no members, the method returns Empty.
- 属性
异常
values
为 null
。values
is null
.
生成的字符串长度超出了允许的最大长度 (MaxValue)。The length of the resulting string overflows the maximum allowed length (MaxValue).
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