calculator.c

#include <stdio.h> /* needed for printf and scanf*/

int main(){
  printf("***************************\n");
  printf(" A SIMPLE CALCULATOR IN C  \n");
  printf("ENTER INPUTS WITHOUT SPACES\n");
  printf("***************************\n\n\n");

  while(1){ /* no booleans (1 == true) */
    /* variables must be declared at a block's head */
    char option;
    double num_1, num_2, total = 0;
    printf("Enter an operation (+, -, *, /) | 'q' to quit: ");
    scanf(" %c", &option); /* scan in the char input (%c) into the address of option */
    if(option == 'q' || option == 'Q') break;
    printf("Enter number 1 (double): ");
    scanf(" %lf", &num_1); /* scan in the double input (%lf) into the address of num_1 */
    printf("Enter number 2 (double): ");
    scanf(" %lf", &num_2); /* scan in the double input (%lf) into the address of num_2 */

    switch(option){
      case '+': total = num_1 + num_2;
      break;
      case '-': total = num_1 - num_2;
      break;
      case '*': total = num_1 * num_2;
      break;
      case '/': total = num_1 / num_2;
      break;
    }
    printf("The result is: %lf\n", total);
  }
  return 0;
}