First C++ Program : Simple Calculator

Question

Usage :

Multiplication

---

Multipliction is simple, Enter your first digit in (eg. 1) Enter your operator (x) Enter your second digit in (eg. 1)

Squaring

---

Enter your first digit in (eg. 1) Enter your operator (s)

Cubing

---

Enter your first digit in (eg. 1) Enter your operator (c)

Division

---

Division is also simple, Enter your first digit in (eg. 1) Enter your operator (/) Enter your second digit in (eg. 1)

Subtraction

---

Enter your first digit in (eg. 1) Enter your operator (-) Enter your second digit in (eg. 1)

Code:

#include <iostream>
using namespace std;
// Function Declaration
int multiply(int firstnumber, int secondnumber, char operation);
int square(int firstnumber, char operation);
int cube(int firstnumber, char operation);
int divide(int firstnumber, int secondnumber, char operation);
int subtract(int firstnumber, int secondnumber, char operation);
int main(){
 // Variable Declaration :
 int number1;
 int number2;
 char operation;
 // User Input :
 cout << "Enter the first number" << endl;
 cin >> number1;
 cout << "Enter the operator" << endl;
 cin >> operation;
 cout << "Enter the second number (leave blank for cube and square)" << endl;
 cin >> number2;
 cout << "This is your sum." << endl;
 cout << number1 << operation << number2 << endl;
 // Calculating :
 int result;
 char m = 'x';
 char sq = 's';
 char c = 'c';
 char d = '/';
 char s = '-';
 if (operation == m) {
 result = multiply(number1, number2, operation);
 } else if (operation == sq) {
 result = square(number1, operation);
 } else if (operation == c) {
 result = cube(number1, operation);
 } else if (operation == d) {
 result = divide(number1, number2, operation);
 } else if (operation == s) {
 result = subtract(number1, number2, operation);
 } else {
 cout << "Wrong operator input. Try again" << endl;
 return 2;
 }
 // Outputing Result :
 cout << "The result is : " << result << endl;
 return 0;
}
// Function Definition
int multiply(int firstnumber, int secondnumber, char operation) {
 return firstnumber * secondnumber;
}
int square(int firstnumber, char operation) {
 return firstnumber * firstnumber;
}
int cube(int firstnumber, char operation) {
 return firstnumber * firstnumber * firstnumber;
}
int divide(int firstnumber, int secondnumber, char operation) {
 return firstnumber / secondnumber;
}
int subtract(int firstnumber, int secondnumber, char operation) {
 return firstnumber - secondnumber;
}

Answer 1

Avoid using using namespace std;

Find more details here why using namespace std; is considered bad practice

Use '\n' for adding newline

std::endl doesn't just add newline but it also flushes the stream. More details about it std::endl vs '\n'

Refactor into functions

Make a function for calculation. What if you'd want to calculate twice? By making it into a function you can simply call it as needed.

Example:

int calculate(...){ ... }
int main(){
 int result1 = calculate(2, 3, 'x');
 int result2 = calculate(2, 'c');
}

Leverage STL

STL functional header has

• std::divides for division.
• std::minus for subtraction.
• std::multiplies for multiplication.
• Example usage:

  std::minus<int>{}(10, 9) // -> 10 - 9 is performed
  std::divides<int>{}(3, 2) // -> 3 / 2 is performed
  

Remove unnecessary parameters from the function.

char operation parameter is never used. It doesn't serve any purpose and can be removed.

switch-case

You could use switch for mapping char to operation. And to avoid writing operation == /*op*/ for each operation in every if and elif.

switch(op){
 case 'x': 
 return std::multiplies<int>{}(num1, num2);
 case '/':
 return std::divides<int>{}(num1, num2);
 case '-':
 return std::minus<int>{}(num1, num2);
 case 'c':
 return cube(num1);
 case 's':
 return sqaure(num1);
 default:
 /* Handle when `op` is other than [-, /, x, c, s] */
};,