gistfile1.c

#include <stdio.h>
int main()
{
  char op;
  double data1,data2,r;
  printf("请输入式子\n");
  scanf("%lf%c%lf",&data1,&op,&data2);
  switch(op)
  {
    case '+':r=data1+data2;break;
    case '-':r=data1-data2;break;
    case '*':r=data1*data2;break;
    case '/':r=data1/data2;break;
  }
 printf("%lf%c%lf=%lf\n",data1,op,data2,r);
}