Type.IsByRef always returning false

Question

I think I don't understand what Type.IsByRef property from .NET is supposed to indicate. I thought it's supposed to return true for reference types and false for value types, so the opposite of Type.IsValueType property. I can't get it to return true for types that are obviously reference types though. Here's an example:

using System.Text;

public class Program
{
    static void Main(string[] args)
    {
        try
        {
            int i = 0;
            Console.WriteLine(i.GetType().IsByRef);    // returns false - OK

            Exception e = new Exception();
            Console.WriteLine(e.GetType().IsByRef);    // returns false - ??

            StringBuilder sb = new StringBuilder();
            Console.WriteLine(sb.GetType().IsByRef);   // returns false - ??
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
        }

        Console.ReadKey(true);
    }
}

What am I missing here?

Answer 1

IsByRef is true for parameters passed by reference:

public void Foo(ref int x) { }
...

var fooMethod = this.GetType().GetMethod("Foo");
var param = fooMethod.GetParameters()[0];
bool isByRef = param.ParameterType.IsByRef; // true

It's unrelated to value types and reference types. To check if a type is a value type, check IsValueType (which returns true for a value type, false otherwise).