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\n",value1 + value2);
		break;
	case'-':
		printf("=%.2f\n",value1 - value2);
	case'*':
		printf("=%.2f\n",value1 * value2);
		break;
	case'/':
		printf("=%.2f\n",value1 / value2);
		break;
	default:
		printf("Unknowm operator\n");
		break;
	}
	return 0;
}