C++ Calculator Program

Question

I'm pretty knew to C++. I'm writing a calculator primarily based upon vectors. I want to have that there is a vector for each operation, and if one of the following operations is called, the value will manipulated by the associated vector. Questions 1. Is my process correct? Am I on the right track? 2. Do I need an alternative method for inputting and checking for a char and an int?

#include <stdio.h>
#include <iostream>
#include <vector>
#include <numeric>
#include <string>
#include <functional>
using namespace std;

vector <int> addition;
vector <int> subtraction;
vector <int> division;
vector <int> multiplication;

char operation;
int input;

int main() {

    cout << "Welcome to my Calculator Program" << endl;
    cout << "Enter your calculation: ";
    void operation();

    return 0;

}

void operation() {
    cin >> operation;
    switch (operation) {
    case '+':
        addition.push_back(input);
        break;
    case '-':
        subtraction.push_back(input);
        break;
    case '/':
        division.push_back(input);
        break;
    case '*':
        multiplication.push_back(input);
        break;
    default:
        cout << "You have entered an invalid operation" << endl;
    }
}

int add(vector <int> addition) {
    for (int i; i > addition.size(); i++) {
        int sum = std::accumulate(addition.begin(), addition.end(), 0);
    }
    return sum;
}

int sub(vector <int> subtraction) {
    for (int i; i > subtraction.size(); i++) {

    }
}

Answer 1

It looks like you're on the right track to me. To answer your second question, no, cin>>variable; automatically attempts to convert user input to the type of variable .

The main problem with this program is that it will not follow order of operations, which makes it pretty useless as a calculator.

You aren't calling operation() when you do void operation(); ; you're declaring it. Nothing will happen except a compiler warning.

The whole idea of std::accumulate() is to avoid looping through a vector or array! Reevaluate if you really need those for loops.

Fix your indentation. The way it is now makes it hard to understand the program's flow. Check out: https://www.cs.northwestern.edu/academics/courses/211/html/c++-style.html#indent

Don't use global variables when you can avoid it, which you definitely can in this case. In this program, it doesn't matter, but it's a really bad habit.

You are using namespace std but still referring to things as std::whatever . That's redundant.

I think you should go back to the textbook and work through some simpler examples. Your logic is (mostly) sound, but you lack a grasp of the syntax. That's nothing to be ashamed of -- C++ is hard and, as you say, you're new -- but you really need to understand that before working on anything more complex than basic examples.

Good luck!