C# List<T>.Insert() Method with Example

C# List<T>.Insert() Method: In this tutorial, we will learn about the Insert() method of List collection with its usage, syntax, and an example using C# program. By IncludeHelp Last updated : April 15, 2023

C# List<T>.Insert() Method

List<T>.Insert() method is used to insert an element at specified index in the list.

Syntax

void List<T>.Insert(int index, T item);

Parameter(s)

It accepts two parameters:

  • index – where you want to insert the element
  • item – to insert in the list

Return Value

It returns nothing – it's return type is void.

Example

int list declaration:
List<int> a = new List<int>();

Adding elements:
a.Add(10);
a.Add(20);
a.Add(30);
a.Add(40);
a.Add(50);
    
Inserting elements at specified indexes
a.Insert(1, 100);
a.Insert(3, 200);
a.Insert(4, 300);
    
Output:
10 100 20 200 300 30 40 50

C# program to insert an element at specified index in the list using List<T>.Insert() method

using System;
using System.Text;
using System.Collections.Generic;

namespace Test {
  class Program {
    static void printList(List <int> lst) {
      //printing elements
      foreach(int item in lst) {
        Console.Write(item + " ");
      }
      Console.WriteLine();
    }

    static void Main(string[] args) {
      //integer list
      List <int> a = new List <int> ();

      //adding elements
      a.Add(10);
      a.Add(20);
      a.Add(30);
      a.Add(40);
      a.Add(50);

      //print the list
      Console.WriteLine("list elements...");
      printList(a);

      //inserting elements at specified indexes
      a.Insert(1, 100);
      a.Insert(3, 200);
      a.Insert(4, 300);

      //list after inserting elements
      Console.WriteLine("list elements after inserting elements...");
      printList(a);

      //hit ENTER to exit
      Console.ReadLine();
    }
  }
}

Output

list elements...
10 20 30 40 50
list elements after inserting elements...
10 100 20 200 300 30 40 50

Reference: List<T>.Insert(Int32, T) Method




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