判断一个成绩的等级

#include<iostream>
using namespace std;
int main()
{
	float i = 0;
	cout << "请输入一个百分制实型成绩:" << endl;
	cin >> i;
	if (i < 0 || i>100)
		cout << "成绩输入错误" << endl;
	else if (i >= 90)
		cout << "优" << endl;
	else if (i >= 80)
		cout << "良" << endl;
	else if (i >= 70)
		cout << "中" << endl;
	else if (i >= 60)
		cout << "及格" << endl;
	else 
		cout << "不及格" << endl;
	return 0;
}