第三章例3-5

#include<stdio.h>
int main(void)
{
	double value1,value2;
	char op;
	printf("Type in an expression:");
	scanf("%lf%c%lf",&value1,&op,&value2);

    if(op=='+')
		printf("=%.2f\n",value1+value2);
	else if(op=='-')
		printf("=%.2f\n",value1-value2);
	else if(op=='*')
		printf("=%.2f\n",value1*value2);
	else if(op=='/')
		printf("=%.2f\n",value1/value2);
	else
		printf("Unknown operator\n");

	return 0;
}