How to remove element from the specified index of the List in C#?

To remove an element from a specified index in a List in C#, you use the RemoveAt() method. This method removes the element at the given index and automatically shifts all subsequent elements one position to the left.

Syntax

Following is the syntax for the RemoveAt() method −

list.RemoveAt(int index);

Parameters

• index − The zero-based index of the element to remove. Must be a valid index (0 ? index < Count).

Using RemoveAt() with String List

The following example demonstrates removing an element at index 5 from a list of strings −

using System;
using System.Collections.Generic;

public class Demo {
   public static void Main(String[] args) {
      List<string> list = new List<string>();
      list.Add("Ryan");
      list.Add("Kevin");
      list.Add("Andre");
      list.Add("Tom");
      list.Add("Fred");
      list.Add("Jason");
      list.Add("Jacob");
      list.Add("David");
      
      Console.WriteLine("Count of elements in the List = " + list.Count);
      Console.WriteLine("Enumerator iterates through the list elements...");
      
      List<string>.Enumerator demoEnum = list.GetEnumerator();
      while (demoEnum.MoveNext()) {
         string res = demoEnum.Current;
         Console.WriteLine(res);
      }
      
      list.RemoveAt(5);
      Console.WriteLine("\nCount of elements in the List [UPDATED] = " + list.Count);
      Console.WriteLine("Enumerator iterates through the list elements...[UPDATED]");
      
      demoEnum = list.GetEnumerator();
      while (demoEnum.MoveNext()) {
         string res = demoEnum.Current;
         Console.WriteLine(res);
      }
   }
}

The output of the above code is −

Count of elements in the List = 8
Enumerator iterates through the list elements...
Ryan
Kevin
Andre
Tom
Fred
Jason
Jacob
David

Count of elements in the List [UPDATED] = 7
Enumerator iterates through the list elements...[UPDATED]
Ryan
Kevin
Andre
Tom
Fred
Jacob
David

Using RemoveAt() with Integer List

The following example shows removing an element at index 2 from a list of integers −

using System;
using System.Collections.Generic;

public class Demo {
   public static void Main(String[] args) {
      List<int> list = new List<int>();
      list.Add(25);
      list.Add(50);
      list.Add(75);
      list.Add(100);
      list.Add(200);
      
      Console.WriteLine("Original List:");
      foreach(int item in list) {
         Console.WriteLine(item);
      }
      
      Console.WriteLine("Count of elements in the List = " + list.Count);
      
      list.RemoveAt(2);
      
      Console.WriteLine("\nUpdated List after removing element at index 2:");
      foreach(int item in list) {
         Console.WriteLine(item);
      }
      Console.WriteLine("Count of elements in the List [UPDATED] = " + list.Count);
   }
}

The output of the above code is −

Original List:
25
50
75
100
200
Count of elements in the List = 5

Updated List after removing element at index 2:
25
50
100
200
Count of elements in the List [UPDATED] = 4

How It Works

When you call RemoveAt(index), the method performs the following operations:

• Removes the element at the specified index

• Shifts all elements after the removed index one position to the left

• Decreases the Count property by 1

• Throws ArgumentOutOfRangeException if the index is invalid

Key Points

• The RemoveAt() method has O(n) time complexity because it needs to shift elements

• Removing from the end of the list is faster than removing from the beginning

• Always ensure the index is valid (0 ? index < list.Count) to avoid exceptions

Conclusion

The RemoveAt() method in C# provides an efficient way to remove elements from a List at a specific index. It automatically handles the shifting of subsequent elements and updates the list count, making it the preferred method for index-based element removal.