使用继承将函数添加到内置类

Question

I'm trying to add a IsImage property that I wrote myself to the HttpPostedFile class, so that if a user is uploading a file, I can do something like this:

FileUpload1.PostedFile.IsImage

How can I do that in C#?

Answer 1

You can use extension methods for that purpose.

public static class HttpPostedFileExtension
{
    public static bool IsImage(this HttpPostedFile file)
    {
        /*your method code goes here*/
    }
}