What is the ArrayList class in C#?

ArrayList class represents an ordered collection of an object that can be indexed individually. It is basically an alternative to an array.

The following are the methods of Arraylist class −

Sr.No	Method & Description
1	public virtual int Add(object value); Adds an object to the end of the ArrayList.
2	public virtual void AddRange(ICollection c); Adds the elements of an ICollection to the end of the ArrayList.
3	public virtual void Clear(); Removes all elements from the ArrayList.
4	public virtual bool Contains(object item); Determines whether an element is in the ArrayList.
5	public virtual ArrayList GetRange(int index, int count); Returns an ArrayList which represents a subset of the elements in the source ArrayList.
6	public virtual int IndexOf(object); Returns the zero-based index of the first occurrence of a value in the ArrayList or in a portion of it.
7	public virtual void Insert(int index, object value); Inserts an element into the ArrayList at the specified index.
8	public virtual void InsertRange(int index, ICollection c); Inserts the elements of a collection into the ArrayList at the specified index.
9	public virtual void Remove(object obj); Removes the first occurrence of a specific object from the ArrayList.
10	public virtual void RemoveAt(int index); Removes the element at the specified index of the ArrayList.
11	public virtual void RemoveRange(int index, int count); Removes a range of elements from the ArrayList.
12	public virtual void Reverse(); Reverses the order of the elements in the ArrayList.
13	public virtual void SetRange(int index, ICollection c); Copies the elements of a collection over a range of elements in the ArrayList.
14	public virtual void Sort(); Sorts the elements in the ArrayList.
15	public virtual void TrimToSize(); Sets the capacity to the actual number of elements in the ArrayList.

Let us see an example of ArrayList −

To sort an ArrayList in C#, use the Sort() method.

The following is the ArrayList −

ArrayList arr = new ArrayList();
arr.Add(32);
arr.Add(12);
arr.Add(55);
arr.Add(8);
arr.Add(13);

Now the Sort() method is used to sort the ArrayList −

arr.Sort();

You can try to run the following code to sort an ArrayList in C# −

Example

using System;
using System.Collections;

namespace Demo {
   class Program {

      static void Main(string[] args) {

         ArrayList arr = new ArrayList();

         arr.Add(89);
         arr.Add(34);
         arr.Add(77);
         arr.Add(90);

         Console.Write("List: ");
         foreach (int i in arr) {
            Console.Write(i + " ");
         }

         Console.WriteLine();
         Console.Write("Sorted List: ");
         arr.Sort();
         foreach (int i in arr) {
            Console.Write(i + " ");
         }
         Console.WriteLine();
         Console.ReadKey();
      }
   }
}

Output

List: 89 34 77 90
Sorted List: 34 77 89 90