CODEWITHSUNDEEP
c#typestypeof
R4D4
R4D4

Reputation: 1402

When is a type not a type? Error: 'is a type, which is not valid in the given context'

Consider the following code, the first call to AcceptType1 compiles fine, however the second call of AcceptType1(XYZ); fails. The specific error is:

Error CS0119 'XYZ' is a type, which is not valid in the given context

I'm not understanding the the specifics behind the error message, and from that I'm failing to understand why the second call fails if XYZ is a type which is exactly what AcceptType1 accepts. If XYZ is a type, then why the need to then call typeof?

public class XYZ
{
}

public class Tester
{

    public void RunTest()
    {
        AcceptType1(typeof(XYZ));
        AcceptType1(XYZ);
    }

    private void AcceptType1(Type t)
    {
        Console.WriteLine(t.ToString());
    }

}

Upvotes: 3

Views: 9322

Answers (2)

asherber
asherber

Reputation: 2713

XYZ may be a type, but it's not a Type, which is what your method expects as a parameter. typeof(XYZ) gives you the Type for the class XYZ.

Upvotes: 1

Daniel A. White
Daniel A. White

Reputation: 190943

XYZ is a symbol or name to the class XYZ. typeof will get the runtime information about the type, which is System.Type. You can also pass type symbols with generics, which doesn't work with typeof:

AcceptType1<T>()

where T can be filled in with a type symbol or name.

Upvotes: 8

Related Questions