C#: Getting size of a value-type variable at runtime?

Question

I know languages such as C and C++ allow determining the size of data (structs, arrays, variables...) at runtime using sizeof() function. I tried that in C# and apparently i

Answer 1

Following on from Cory's answer, if performance is important and you need to hit this code a lot then you could cache the size so that the dynamic method only needs to be built and executed once per type:

int x = 42;
Console.WriteLine(Utils.SizeOf(x));    // Output: 4

// ...

public static class Utils
{
    public static int SizeOf(T obj)
    {
        return SizeOfCache.SizeOf;
    }

    private static class SizeOfCache
    {
        public static readonly int SizeOf;

        static SizeOfCache()
        {
            var dm = new DynamicMethod("func", typeof(int),
                                       Type.EmptyTypes, typeof(Utils));

            ILGenerator il = dm.GetILGenerator();
            il.Emit(OpCodes.Sizeof, typeof(T));
            il.Emit(OpCodes.Ret);

            var func = (Func)dm.CreateDelegate(typeof(Func));
            SizeOf = func();
        }
    }
}