What are extension methods in C# and how do I use them?

What are extension methods in C# and how do I use them?

Extension methods in C# allow you to add new methods to existing types without modifying their source code. You define them in a static class and use the 'this' keyword in the first parameter.

Can you give me an example of an extension method?

Sure! Here's a simple example:

public static class StringExtensions
{
    public static int WordCount(this string str)
    {
        return str.Split(new char[] {' '}, StringSplitOptions.RemoveEmptyEntries).Length;
    }
}

You can then call myString.WordCount() to get the number of words in myString.

Are there any limitations to using extension methods?

Yes, extension methods cannot access private members of the class they extend. They also cannot override existing methods.

When should I use extension methods?

Use extension methods when you want to add functionality to existing types in a clean and maintainable way, especially when you don't have access to modify the original type.