An callback simple example with C++ to undertanding how it works and its aspects.

callback.cpp

/* Callback example with c++ */
#include <iostream>

int add(int a, int b, const char *caller_name)
{
	std::cout << __FUNCTION__ << " was called by "  << caller_name << "\n";
	return a + b;
}

int subtraction(int a, int b, const char *caller_name)
{
	std::cout << __FUNCTION__ << " was called by "  << caller_name << "\n";
	return a - b;
}

int operation(int a, int b, int (*func)(int, int, const char *), const char *caller_name)
{
	std::cout << __FUNCTION__ << " was called by "  << caller_name << "\n";
	int x = (*func)(a, b, __FUNCTION__);
	return x;
}

int main()
{
	int x, y;
	int (*minus)(int, int, const char *) = subtraction;
	x = operation(10, 20, add, __FUNCTION__);
	y = operation(x, 2, minus, __FUNCTION__);
	std::cout << y << "\n";
	return 0;
}