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String.Join Method (String, String[])

Concatenates all the elements of a string array, using the specified separator between each element.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

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

Parameters

separator
Type: System.String

The string to use as a separator. separator is included in the returned string only if value has more than one element.

value
Type: System.String[]

An array that contains the elements to concatenate.

Return Value

Type: System.String
A string that consists of the elements in value delimited by the separator string. If value is an empty array, the method returns String.Empty.

ExceptionCondition
ArgumentNullException

value is null.

For example, if separator is ", " and the elements of value are "apple", "orange", "grape", and "pear", Join(separator, value) returns "apple, orange, grape, pear".

If separator is null, an empty string (String.Empty) is used instead. If any element in value is null, an empty string is used instead.

The following example demonstrates the Join method.

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  

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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