#include
void main()
{double x,y;
char op;
printf("输入你要计算的式子(2个数的四则运算)如11.2-3.1并回车:");
scanf("%lf%c%lf",&x,&op,&y);
switch(op)
{case'+':printf("%f+%f=%f\n",x,y,x+y);break;
case'-':printf("%f-%f=%f\n",x,y,x-y);break;
case'*':printf("%f*%f=%f\n",x,y,x*y);break;
case'/':if(y==0)
printf("无意义");
else
printf("%f/%f=%f\n",x,y,x/y);break;
default:printf("运算符号无意义");
}
}