C:简易计算器，内蒙古，892，1908，程序设计

#include<stdio.h>
int main(){
	int ch,num1,num2;
	while(printf("请输入指令，1-加，2-减，3-乘，4-除，5-退出\n"),scanf("%d",&ch),ch!=5){
		int sum;
		scanf("%d %d",&num1,&num2); 
		switch(ch){
			case 1: sum=num1+num2;break;
			case 2: sum=num1-num2;break;
			case 3: sum=num1*num2;break;
			case 4: sum=num1/num2;
		}
		printf("运算结果为：%d\n",sum);
	}
	return 0;
} 

#include<stdio.h>
int main(){
	int ch,num1,num2;
	while(1){
		printf("请输入指令，1-加，2-减，3-乘，4-除，5-退出\n");
		scanf("%d",&ch);
		if(ch==5) break; 
		scanf("%d %d",&num1,&num2); 
		int sum;
		switch(ch){
			case 1: sum=num1+num2;break;
			case 2: sum=num1-num2;break;
			case 3: sum=num1*num2;break;
			case 4: sum=num1/num2;
		}
		printf("运算结果为：%d\n",sum);
	}
	return 0;
}