Extension methods in LINQ

Shweta Kuthi

15y2.2kLINQ

Why Extensions method are used in LINQ?

3 Replies

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Jignesh Trivedi14y ago
hi,

Extension method used to customize, behaviour of exsiting and new method which is used frequently.

for example.

string have ToString() method, as we know that ToString does not handle null condition. you may write your extension method which may also handle null.

it help us to reduce code(like functions).

hope this help.
Vulpes15y ago
Extension methods are useful in LINQ because they allow you to chain operations on a sequence, with the results of each operation being fed to the next operation in the chain.

Although you can achieve the same result with 'ordinary' static methods, you cannot chain the operations in the same 'seemless' way. For example, if there were no extension methods, you could do:

int[] numbers = {1, 2, 3, 4};
IEnumerable evenNumbers = Enumerable.Where(numbers, n => n % 2 == 0);
evenNumbers = Enumerable.OrderByDescending(evenNumbers, n => n);
foreach(int n in evenNumbers) Console.Write("{0} ", n); // 4 2

We can simplify this using extension methods as follows:

int[] numbers = {1, 2, 3, 4};
IEnumerable evenNumbers = numbers.Where(n => n % 2 == 0).OrderByDescending(n => n);
foreach(int n in evenNumbers) Console.Write("{0} ", n); // 4 2

Of course, extension methods really are static methods but the C# compiler allows them to be used as if they were instance methods of the object represented by the 'this' parameter.
Pravin More15y ago
Hi Shweta,
                 Extension methods are used to change behaviour of existing .net type according to need means you can customize it.
                 For example, you may decide that you don't like the way where works, so you add a new where to your code that provides the functionality you want. This feature can significantly change the way LINQ works and make your coding significantly easier by customizing it.

             e.g   IEnumerable result = customers.Where(customer => customer.FirstName == "pravin");

Thanx,hope it will help you.
Pravin.