switch-case的简单计算器

#include <stdio.h>

int main( )

{

double a, b;

  char op;

  scanf("%lf%c%lf", &a, &op, &b);

  switch (op)

  {

      case  '+':

    printf("%lf + %lf = %lf\n", a, b, a + b);

  break;

  case  '-':

    printf("%lf - %lf = %lf\n", a, b, a - b);

  break; 

  case  '*':

printf("%lf * %lf = %lf\n", a, b, a * b);

  break;

  case  '/':

  if (b != 0)

  printf("%lf / %lf = %lf\n", a, b, a / b);

  else

    printf("除数不能是0! \n");

  break;

  }

}