11

Calculator with 5 operations

Mean of the positive numbers input from the keyboard  |  Convert a floating-point number to an integer

calc.c
  1. #include <stdio.h>
  2.  
  3. main() {
  4.     int x, y, r;
  5.     char op;
  6.  
  7.     printf( "Enter an operation (x [+-*/%%] y): " );
  8.  
  9.     if ( scanf("%d %c %d", &x, &op, &y ) == 3 ) {
  10.         switch ( op ) {
  11.             case '+':
  12.                 r = x + y;
  13.                 break;
  14.             case '-':
  15.                 r = x - y;
  16.                 break;
  17.             case '*':
  18.                 r = x * y;
  19.                 break;
  20.             case '/':
  21.                 if ( y == 0 )
  22.                     goto error;
  23.                 r = x / y;
  24.                 break;
  25.             case '%':
  26.                 if ( y == 0 )
  27.                     goto error;
  28.                 r = x % y;
  29.                 break;
  30.             default:
  31.                 goto error;
  32.         }
  33.         printf("%d %c %d = %d\n", x, op, y, r);
  34.     }
  35.     else
  36. error:
  37.         printf("What?\n");
  38. }
$ gcc -o calc calc.c
$ ./calc 
Enter an operation (x [+-*/%] y): 2 + 3
2 + 3 = 5
$ ./calc 
Enter an operation (x [+-*/%] y): 2 - 3
2 - 3 = -1
$ ./calc
Enter an operation (x [+-*/%] y): -2 * -3
-2 * -3 = 6
$ ./calc
Enter an operation (x [+-*/%] y): 2/3  
2 / 3 = 0
$ ./calc
Enter an operation (x [+-*/%] y): -2 % 3  
-2 % 3 = -2
$ ./calc
Enter an operation (x [+-*/%] y): 1.5 * 2
What?

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