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Purpose of "FirstOrDefault" Operator in LINQ

The FirstOrDefault operator in LINQ serves the purpose of retrieving the first element from a sequence (such as a list or an array) that satisfies a given condition. If no matching element is found, it returns the default value for the type of elements in the sequence. This operator is useful when you want to find an element that meets a condition or provide a default value if there's no match, all without throwing an exception.

Code Example (C#)


using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<int> numbers = new List<int> { 1, 2, 3, 4, 5 };

        // Using FirstOrDefault
        int firstOrDefaultElement = numbers.FirstOrDefault(x => x % 2 == 0); // Finding the first even number
        Console.WriteLine("First Element (FirstOrDefault): " + firstOrDefaultElement);

        // Using FirstOrDefault with a default value
        int firstOrDefaultWithDefault = numbers.FirstOrDefault(x => x > 10, -1); // No element > 10, custom default value (-1)
        Console.WriteLine("First Element (FirstOrDefault with default): " + firstOrDefaultWithDefault);
    }
}

Output


First Element (FirstOrDefault): 2
First Element (FirstOrDefault with default): -1

In this code example, we used FirstOrDefault to find the first even number in the list (which is 2) and to find an element greater than 10 (which doesn't exist in the list) with a custom default value of -1.

The FirstOrDefault operator makes it easy to query sequences and handle scenarios where you may or may not find a matching element without causing exceptions.

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