#include <iostream>

namespace math
{
    double add (double x, double y) {return x + y;} // an add function. pass to parameters to it and
                                       // it will return the value of the two added together
    double subtract (double x, double y) {return x - y;} // a subtract function
    double multiply (double x, double y) {return x * y;}
    double divide (double x, double y) {return x / y;}
} // end of the namespace

// now a few ways to be using our namespace
// we could be "using namespace math;"
// but say if I only want to access the add function
// from our math namespace. What then?
using math::add;
// the :: operator means scope.
// math::add means that "add" is a part of our math namespace

int main ()
{
    // since we aren't using namespace std, and we want to access cout, we can still
    // do it by adding "std::" in front of cout, meaning the our program needs to search
    // in the std namespace to find cout
    std::cout << add (4,3) << '\n'; // call our function and add a new line to output
    // now, the following line will give an error
    // std::cout << subtract (4,3);
    // why? because we haven't used subtract, or prefixed it with our scope operator
    // however, we could do this:
    std::cout << math::subtract (4,3);
}