C# String Join()

The Join() method joins the elements of an array using a specified separator.

Example

using System;  
namespace CsharpString {  
  class Test {
    public static void Main(string [] args) {
   
      // creates a string array.
      string[] text = { "C#", "Java", "C++" };
        
// joins string with space between them Console.WriteLine(String.Join(" ", text));
Console.ReadLine(); } } } // Output: C# Java C++

Join() Syntax

The syntax of the string Join() method is:

String.Join(String separator, String[] value, Int32 startIndex, Int32 count)

Here, Join() is a method of class String.


Join() Parameters

The Join() method takes the following parameters:

  • separator - the separator to join the elements
  • value - an array of strings to join
  • startIndex - the first item in value to join
  • count - number of elements to join (starts from startIndex)

Join() Return Value

  • returns a string that consists of the elements separated by the separator

Example 1: C# String Join()

using System;  
namespace CsharpString {  
  class Test {
    public static void Main(string [] args) {
   
      // creates a string array.
      string[] text = {"C#", "Java", "C++"};
        
// joins string with "/" between them string result = String.Join("/", text);
Console.WriteLine(result); Console.ReadLine(); } } }

Output

C#/Java/C++

Here, the text elements "C#", "Java", and "C++" to the Join() are joined using the / separator.


Example 2: Join() With Start Index and Count

using System;  
namespace CsharpString {  
  class Test {
    public static void Main(string [] args) {
   
      // Creating a string array
      string[] text = {"C#", "Java", "C++", "Swift", "Go"};

// joins 2 strings from index 1 string s1 = String.Join("-", text, 1, 2);
Console.WriteLine(s1); Console.ReadLine(); } } }

Output

Java-C++

In the above example, notice the line,

string s1 = String.Join("-", text, 1, 2);

Here,

  • 1 - starting index of text to join (index of "Java")
  • 2 - number of elements to join
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