Question

extern "C" int func(int *, Foo);

This is from a sample code from class. But I don’t understand how the interface is working, one with no variable name, the other with no type. How is that going to work?

Answer 1

When declaring functions you don’t need to specify a parameter name, just a type. Foo in this case is a type.

extern "C" tells the compiler it should use a C-style symbol, which more or less means it won’t be using name mangling (which C++ uses to allow multiple functions share a name, but use different parameter sets or namespaces).