c_cpp_programming.md

C/C++ Programming

Variable Argument Macros in C/C++

#define some_macro(A,B,...) called_func(A,B,__VA_OPT__(,) __VA_ARGS__)

__VA_ARGS__ expands to the arguments. __VA_OPT__ expands to the passed string only if one of more variable arguments are passed. This allows you to only add syntactic elements in the case they're need to support a non-empty arguments block.

Function pointers (std::bind)

std::bind is the mechanism used to create a function pointer with bound arguments in c++.

Member function pointers

The mechanism is useful for creating a function pointer to a member function of an object with the object instance embedded within the pointer. In this case the first bound argument should be the object:

class SomeClass {
  int some_function(int a);
};

SomeClass some_instance;

auto f=std::bind(&SomeClass:some_function,&some_instance);

Function pointers with unbound arguments

Return type

While the c++ specification does not give an explicit return type for std::bind, it can be stored using a std::function<...> with the correct template types.

Function pointers (std::function)

Syntax:

std::function<SomeReturnType(SomeArgType0,SomeArgType1,...)>