例3-11

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

 printf("Type in an expression:");  scanf("%lf%c%lf",&valuel,&op,&value2);  if(op=='+')   printf("=%.2f\n",valuel,&op,&value2);  else if(op=='-')   printf("=%.2f\n",valuel-value2);  else if(op=='*')   printf("=%.2f\n",valuel*value2);  else if(op=='/')   if(value2!=0)    printf("=%.2f\n",valuel/value2);   else    printf("Divisor can not be 0!\n");  else   printf("Unknown operator!\n");  return 0; }