第三章例3-9

#include<stdio.h>
int main(void)
{
   double value1,value2;
   char op;

   printf("Type in an expression:");
   scanf("%lf%c%lf",&value1,&op,&value2);
   switch(op){
       case'+':
           printf("=%.2f
",value1+value2);
           break;
       case'-':  
           printf("=%.2f
",value1-value2);
           break;
       case'/':
            printf("=%.2f
",value1/value2);
            break;
       default:
             printf("Unknown operator
");
             break;
   }
   return 0;
}