怎样用VC++编写计算器?

#include
void main()
{
double number1=0.0;
double number2=0.0;
char operation=0;
printf("\nEnter the calculation\n");
scanf("%lf%c%lf",&number1,&operation,&number2);
switch(operation)
{
case'+':
printf("=%lf\n",number1+number2);
break;
case'-':
printf("=%lf\n",number1-number2);
break;
case'*':
printf("=%lf\n",number1*number2);
break;
case'/':
if(number2==0)
printf("\n\n\aPivision by zero error!\n");
else
printf("=%lf\n",number1/number2);
break;
case'%':
if((long)number2==0)
printf("\n\n\a Division by zero error!\n");
else
printf("=%ld\n",(long)number1/(long)number2);
break;
default:
printf("\n\n\aIllegal operation!\n");
}

}