How to find the return type of a function?

So 开发者_开发问答__FUNCTION__ tells us the name of the current function. Is there a similar macro for return type of the function?

Since you already use a Visual-C++ specific __FUNCTION__ macro you could look into __FUNCSIG__ macro - it expands into the full signature which you could then parse and extract the return type. There's no macro that would do that on itself in Visual C++.

If you don't need it at preprocessing time:
In C++0x, you can do use decltype(myFunc(dummyparams)), which stands for the return type of myFunc (compile-time).
If you now want a string out of that, enable RTTI (run-time type information) and use typeid().name() (run-time):

#include <typeinfo>

double myFunc(){
  // ...
  return 13.37;
}

int main(){
  typedef decltype(myFunc()) myFunc_ret;
  char const* myFunc_ret_str = typeid(myFunc_ret).name();
}

Note, however, that the myFunc_ret_str isn't always a clean name of the return type - it depends on how your compiler implements typeid.

Seeing the function itself you can know the return type. After all, MACRO works even before compile time, that means, when you write the MACRO you do know the return type of the function only if you look at it.

If I tell you that you can use __FUNCSIG__, even then you do know the return type at the moment you use it in your code.

However if you need to know it in template programming, then I would suggest you to look at : decltype

C++11:

template < typename R, typename ...Args >
char const* FunctionReturnTypeAsString( R foo(Args...) ) {
  return typeid(R).name()
}