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Purpose of "LastOrDefault" in LINQ

The "LastOrDefault" operator in LINQ serves the purpose of retrieving the last element from a sequence that satisfies a specified condition or returning a default value if no such element exists. It is used when you need to access the last element that meets a certain condition within a collection or sequence, and you want to handle the case where no matching element is found.

Imagine you have a collection of data, and you want to access the last item that meets a specific criterion. "LastOrDefault" is particularly useful in scenarios where you are uncertain if there will be a matching element or not. It ensures you get the last matching element or a specified default value if there are no matches.

Let's illustrate the purpose of "LastOrDefault" with a complete source code example:


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

class Program
{
    static void Main()
    {
        // Sample collection of names
        List<string> names = new List<string> { "Alice", "Bob", "Charlie", "David", "Eve", "Frank" };

        // Attempt to find the last name starting with 'C' in the collection
        string lastNameStartingWithC = names.LastOrDefault(name => name.StartsWith("C"));

        // Output the result
        if (!string.IsNullOrEmpty(lastNameStartingWithC))
        {
            Console.WriteLine($"The last name starting with 'C' is: {lastNameStartingWithC}");
        }
        else
        {
            Console.WriteLine("No name starting with 'C' found.");
        }
    }
}

Output:


The last name starting with 'C' is: Charlie

In this example:

  • We have a list of names.
  • We use the "LastOrDefault" operator with a condition to find the last name starting with 'C'.
  • The condition (name.StartsWith("C")) ensures that we want to find the last name meeting this criterion.
  • Since there is a name "Charlie" that meets the condition, it successfully returns that name.
  • If there were no names starting with 'C', it would return the default value for the data type (null in this case).

The "LastOrDefault" operator is helpful when you need to access the last element that matches a condition within a sequence and want to gracefully handle cases where there might be no matching elements. It ensures you get the last matching element or a specified default value.

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