calculate.cpp

#include <iostream>

int getUserInput() {
  std::cout << "Please input an integer: ";
  int value;
  std::cin >> value;
  return value;
}

int getMathematicalOperation() {
  std::cout << "Please enter which operator you want. (1 = +, 2 = -, 3 = *, 4 = /): ";

  int op;
  std::cin >> op;

  // What if the user enters an invalid character?
  // We'll ignore this possibility for now

  return op;
}

int calculateResult(int x, int op, int y) {
  switch(op){
   case 1:
      return x + y;

   case 2:
      return x - y;

   case 3:
      return x * y;

   case 4:
      return x / y;
  }

  return -1;
}

void printResult(int result) {
  std::cout << "Your result is: " << result << std::endl;
}

int main()
{
  // Get first number from user.
  int input1 = getUserInput();

  // Get mathematical operator from user.
  int op = getMathematicalOperation();

  // Get second number from user.
  int input2 = getUserInput();

  // Calculate Result.
  int result = calculateResult(input1, op, input2);
  printResult(result);

}