Get the number of elements contained in Collection in C#

The Count property in C# provides a simple way to determine the number of elements contained in a Collection<T>. This property is available for all collection types that implement the ICollection<T> interface and returns an integer value representing the current element count.

Syntax

Following is the syntax for using the Count property −

Collection<T> collection = new Collection<T>();
int count = collection.Count;

Using Count with String Collection

The following example demonstrates how to get the count of elements in a string collection −

using System;
using System.Collections.ObjectModel;

public class Demo {
   public static void Main() {
      Collection<string> col = new Collection<string>();
      col.Add("Andy");
      col.Add("Kevin");
      col.Add("John");
      col.Add("Kevin");
      col.Add("Mary");
      col.Add("Katie");
      col.Add("Barry");
      col.Add("Nathan");
      col.Add("Mark");
      Console.WriteLine("Count of elements = "+ col.Count);
      Console.WriteLine("Iterating through the collection...");
      var enumerator = col.GetEnumerator();
      while (enumerator.MoveNext()) {
         Console.WriteLine(enumerator.Current);
      }
   }
}

The output of the above code is −

Count of elements = 9
Iterating through the collection...
Andy
Kevin
John
Kevin
Mary
Katie
Barry
Nathan
Mark

Using Count with Integer Collection and Dynamic Updates

This example shows how the Count property updates dynamically as elements are added or removed from the collection −

using System;
using System.Collections.ObjectModel;

public class Demo {
   public static void Main() {
      Collection<int> col = new Collection<int>();
      col.Add(10);
      col.Add(20);
      col.Add(30);
      col.Add(40);
      col.Add(50);
      col.Add(60);
      col.Add(70);
      col.Add(80);
      Console.WriteLine("Elements in the Collection...");
      foreach(int val in col) {
         Console.WriteLine(val);
      }
      Console.WriteLine("Does the collection has the element 70? = "+col.Contains(70));
      Console.WriteLine("Count of elements = " + col.Count);
      col.Clear();
      Console.WriteLine("Count of elements (updated) = " + col.Count);
   }
}

The output of the above code is −

Elements in the Collection...
10
20
30
40
50
60
70
80
Does the collection has the element 70? = True
Count of elements = 8
Count of elements (updated) = 0

Count vs Length vs Size

Conclusion

The Count property provides an efficient way to determine the number of elements in a Collection<T>. It updates automatically as elements are added or removed, making it ideal for tracking collection size dynamically during runtime operations.