C# FAQ: testing if a generic type parameter is of particular type

Today's blog post is a quick C# frequently asked question and a tip for better code. The question is: if you have a generic method that uses a type definition "T" for a return type of the method, how can you successfully test whether "T" is of particular type?

The correct and easiest way to do this is to say:

private T MyGenericMethod(string valueA, string valueB)
{
    if (typeof(T) == typeof(int))
    {
       // T is an "int"
       ...
    }
    else
    {
        throw new InvalidOperationException("The generic type T is not of a known type");
    }

    ...
}

Here, the type "T" is tested whether it is an integer type (System.Int32).

Note that while the C#'s handy is operator can be used to test for type matches, it does not work with generic type parameters.

Happy coding!