C# | Add an object to the end of Collection<T>

Last Updated : 11 Jul, 2025
Collection<T>.Add(T) method is used to add an object to the end of the Collection<T>. Syntax : 
public void Add (T item);
Here, item is the object to be added to the end of the Collection<T>. The value can be null for reference types. Below given are some examples to understand the implementation in a better way: Example 1: CSHARP 
// C# code to add an object to
// the end of the Collection
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

class GFG {

    // Driver code
    public static void Main()
    {
        // Creating a collection of strings
        Collection<string> myColl = new Collection<string>();

        myColl.Add("A");
        myColl.Add("B");
        myColl.Add("C");
        myColl.Add("D");
        myColl.Add("E");

        // Displaying the number of elements in Collection
        Console.WriteLine("The number of elements in myColl are : " 
                                                   + myColl.Count);

        // Displaying the elements in Collection
        Console.WriteLine("The elements in myColl are : ");

        foreach(string str in myColl)
        {
            Console.WriteLine(str);
        }
    }
}
Output: 
The number of elements in myColl are : 5
The elements in myColl are : 
A
B
C
D
E
Example 2: CSHARP 
// C# code to add an object to
// the end of the Collection
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

class GFG {

    // Driver code
    public static void Main()
    {
        // Creating a collection of ints
        Collection<int> myColl = new Collection<int>();

        myColl.Add(2);
        myColl.Add(3);
        myColl.Add(4);
        myColl.Add(5);

        // Displaying the number of elements in Collection
        Console.WriteLine("The number of elements in myColl are : "
                                                   + myColl.Count);

        // Displaying the elements in Collection
        Console.WriteLine("The elements in myColl are : ");

        foreach(int i in myColl)
        {
            Console.WriteLine(i);
        }
    }
}
Output: 
The number of elements in myColl are : 4
The elements in myColl are : 
2
3
4
5
Note:
  • Collection<T> accepts null as a valid value for reference types and allows duplicate elements.
  • This method is an O(1) operation.
Reference:
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