Lists in C#

In this article, we will learn about the List class.

The List is a collection of strongly typed objects that can be accessed by index and having methods for sorting, searching, and modifying list. It comes under System.Collection.Generic namespace.

Creating a List

We create a list in C# using the following syntax:
List<T> l1 = new List<T>();
<T> here denotes any datatype of which we want to create a list of.

Properties of List

• Count: This property gets the number of nodes actually contained in the List.</li>
• Capacity: Gets or sets the total number of elements the internal data structure can hold without resizing..
• List[Int32]: Gets or sets the element at the specified index.
</ul>

---

Methods of List

• Add(T): Adds the element at the end of the List.</li>
• AddRange(IEnumerable)</code>: Adds the elements of the specified collection to the end of the List.</li>
• Contains(T): Determines whether a value is in the List.</li>
• Remove(T): Removes the first occurrence of the specified value from the List.</li>
• RemoveAt(ind): Removes the element at the specified index.
• Sort(): Sorts the elements in the entire List using the default comparer.</li>
• Insert(ind, T): Inserts T at the specified index.
• Clear(): Removes all the elements from the List.</li> </ul>

  ---

  List Operation Examples:

  Different List operations are demonstrated in the example below:

  using System;
  using System.Collections.Generic;
  namespace ListDemo {
      class Example {
          static void Main(string[] args) {
              List < int > L = new List < int > ();
              L.Add(5);          // Adds to the end
              L.Add(2);          
              L.Add(4);
              L.Add(9);
              foreach(int i in L) {
                  Console.Write(i + " ");
              }
              Console.WriteLine();
              L.Sort();                // Sorts the list in ascending order
              foreach(int i in L) {
                  Console.Write(i + " ");
              }
              Console.WriteLine();
              L.RemoveAt(1);           // Removes the elements from the 1st index
              L.Remove(9);             // Removes first occurenece of 9
              foreach(int i in L) {
                  Console.Write(i + " ");
              }
              Console.WriteLine();
              Console.WriteLine(L.Contains(2));    // Checks if 2 is present in the list
              Console.WriteLine(L.Count);          // Count returns the number of elements present
          }
      }
  }
  

  Output:

  5 2 4 9
2 4 5 9
2 5
True
2
  

  ---

  Task

  In the editor below, perform the different tasks as directed.