Marshaling – what is it and why do we need it?

Question

What is marshalling and why do we need it?

I find it hard to believe that I cannot send an int over the wire from C# to C and have to marshall it. Why can't C# just send the 32 bits over with a starting and terminating signal, telling C code that it has received an int?

_{If there are any good tutorials or sites about why we need marshalling and how to use it, that would be great.}

Answer 1

Because different languages and environments have different calling conventions, different layout conventions, different sizes of primitives (cf. char in C# and char in C), different object creation/destruction conventions, and different design guidelines. You need a way to get the stuff out of managed land an into somewhere where unmanaged land can see and understand it and vice versa. That's what marshalling is for.