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What is the purpose of "Count" operator in LINQ?

The Count operator in LINQ serves the purpose of counting the number of elements in a collection or sequence that satisfy a specified condition. It allows you to determine how many items in the collection meet a certain criteria without the need to iterate through the entire collection manually.

In simple terms, it helps you answer questions like "How many items in this list meet a specific condition?" For example, the Count operator can be applied to determine the number of students who achieved scores surpassing a specified grade, the quantity of products currently available in inventory, or how many users have a certain attribute.

Here's the syntax of the Count operator in LINQ: 


int count = sequence.Count(element => condition);
  • sequence represents the collection or sequence of elements that you want to count.
  • element => condition is a lambda expression or delegate that specifies the condition to evaluate for each element in the sequence.

Example:


using System;
using System.Linq;

class Program
{
    static void Main()
    {
        // Define an array of integers
        int[] numbers = { 1, 2, 3, 4, 5 };

        // Use LINQ to count the even numbers in the array
        int evenCount = numbers.Count(num => num % 2 == 0);

        // Display the count of even numbers
        Console.WriteLine("Count of even numbers in the array: " + evenCount);
    }
}

Output:


Count of even numbers in the array: 2

In this example, the Count operator is used to count the number of even numbers in the numbers array. The lambda expression num => num % 2 == 0 is the condition to be evaluated for each element. The result is 2 because there are two even numbers in the array.

The Count operator is useful when you need to determine the quantity of elements that satisfy a specific condition. It provides a convenient way to perform counting operations without requiring manual iteration or additional logic.

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