// main.cpp
#include <iostream>
#include "calculator.h"

using namespace std;

int main()
{
    string operacje[4];
    operacje[0] = "add";
    operacje[1] = "sub";
    operacje[2] = "mul";
    operacje[3] = "div";

    cout << calculate(3.5, 2, operacje, 4);

    return 0;
}

// calculator.h
#ifndef CALCULATOR_H_INCLUDED
#define CALCULATOR_H_INCLUDED
#include <iostream>

using namespace std;

float add(float x, float y);
float subtract(float x, float y);
float multiply(float x, float y);
float divide(float x, float y);
float calculate(float x, float y, string operations[], unsigned int size);

#endif // CALCULATOR_H_INCLUDED

// calculator.cpp
#include "calculator.h"

float add(float x, float y)
{
    return x + y;
}

float subtract(float x, float y)
{
    return x - y;
}

float multiply(float x, float y)
{
    return x * y;
}

float divide(float x, float y)
{
    return x / y;
}

float calculate(float x, float y, string operations[], unsigned int size)
{
    float wynik = 0;
    for(unsigned int i = 0; i < size; ++i)
    {
        if(operations[i] == "add")
            wynik += add(x, y);
        else if(operations[i] == "sub")
            wynik += subtract(x, y);
        else if(operations[i] == "mul")
            wynik += multiply(x, y);
        else if(operations[i] == "div")
            wynik += divide(x, y);
    }
    return wynik;
}