calculate

#include <iostream>
const int numberOfFoos = 4;
double calculate(double x, double y, double (*ps)(double, double));

double add(double x, double y);
double subtract(double x, double y);
double divide(double x, double y);
double multiply(double x, double y);
double (*pf[numberOfFoos])(double, double) = {add, subtract, divide, multiply};
int main()
{
    double first, second;
    std::cin >> first;
    std::cin >> second;
    for(int i = 0; i<numberOfFoos; i++)
    {
        double q = calculate(first, second, pf[i]);
        std::cout << q << "\n";
    }
    return 0;
}

double add(double x, double y)
{
    return x + y;
}
double subtract(double x, double y)
{
    return x - y;
}
double divide(double x, double y)
{
    return x/y;
}
double multiply(double x, double y)
{
    return x*y;
}
double calculate(double x, double y, double (*ps)(double, double))
{
    return ps(x, y);
}