Collapse the table of content
Expand the table of content
Expand Minimize
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

String.Join Method (String, String[], Int32, Int32)


Concatenates the specified 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,
	string[] value,
	int startIndex,
	int count


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.

Type: System.String[]

An array that contains the elements to concatenate.

Type: System.Int32

The first element in value to use.

Type: System.Int32

The number of elements of value to use.

Return Value

Type: System.String

A string that consists of the strings in value delimited by the separator string.


String.Empty if count is zero, value has no elements, or separator and all the elements of value are String.Empty.

Exception Condition

value is null.


startIndex or count is less than 0.


startIndex plus count is greater than the number of elements in value.


Out of memory.

For example, if separator is ", " and the elements of value are "apple", "orange", "grape", and "pear", Join(separator, value, 1, 2) returns "orange, grape".

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 concatenates two elements from an array of names of fruit.

// Sample for String.Join(String, String[], int int)
using System;

class Sample {
    public static void Main() {
    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'

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Return to top
© 2015 Microsoft