计算器（虽然没用）

#include <bits/stdc++.h>
using namespace std;
double xsjf(double x, double y){
	return x + y;
}
double xshjf(double x, double y){
	return x - y;
}
double xscf(double x, double y){
	return x * y;
}
double xshcf(double x, double y){
	return x / y;
}
int main(){
	int i, x, y, n = 1;
	double xx, yy;
	char xz;
	cout << "欢迎使用简单计算器（功能不全，只能两个数计算）" << endl;
	while(n){
		cout << "请选择算法：1.加法 2.减法 3.乘法 4.除法" << endl;
		cin >> i;
		if(i == 1){
			cout << "请输入两个数：";
			cin >> x >> y;
			cout << xsjf(x, y) << endl;
			cout << "是否继续？（Y/N）" << endl;
			while(1){
				cin >> xz;
				if(xz != 'Y' && xz != 'N'){
					cout << "无效输入";
			    	system("cls");
				}
				if(xz == 'N'){
					return 0;
				}
				if(xz == 'Y'){
					break;
				}
			}
	    	system("cls");
		}
		if(i == 2){
			cout << "请输入两个数：";
			cin >> x >> y;
			cout << xshjf(x, y) << endl;
			cout << "是否继续？（Y/N）" << endl;
			cin >> xz;
			while(1){
				cin >> xz;
				if(xz != 'Y' || xz != 'N'){
					cout << "无效输入";
			    	system("cls");
				}
				if(xz == 'N'){
					return 0;
				}
				if(xz == 'Y'){
					break;
				}
			}
		    system("cls");
		}
		if(i == 3){
			cout << "请输入两个数：";
			cin >> x >> y;
			cout << xscf(x, y) << endl;
			cout << "是否继续？（Y/N）" << endl;
			cin >> xz;
			while(1){
				cin >> xz;
				if(xz != 'Y' || xz != 'N'){
					cout << "无效输入";
			    	system("cls");
				}
				if(xz == 'N'){
					return 0;
				}
				if(xz == 'Y'){
					break;
				}
			}
		    system("cls");
		}
		if(i == 4){
			cout << "请输入两个数：";
			cin >> x >> y;
			cout << xshcf(x, y) << endl;
			cout << "是否继续？（Y/N）" << endl;
			cin >> xz;
			while(1){
				cin >> xz;
				if(xz != 'Y' || xz != 'N'){
					cout << "无效输入";
			    	system("cls");
				}
				if(xz == 'N'){
					return 0;
				}
				if(xz == 'Y'){
					break;
				}
			}
		    system("cls");
		}
	}
	return 0;
}