How is possible to deduce function argument type in C++?

Question

Having the function definition:

void f(int) { }

I want to define:

int a;

but if the function definition c

Answer 1

It depends on what you want to do, where that variable shall be used. If it is in the function a template might be a good choice:

template
void foo(T ) {
    T a;
}

Alternatively if you are outside the function and have the requirement to really know this you can use Boost.TypeTraits, i.e. function_traits::arg1_type will give int