c++程序—switch分支

#include<iostream>
using namespace std;
#include<string>

int main()
{
    //多元分支
    cout << "请输入学生的分数:" << endl;
    int score;
    cin >> score;
    cout << "您输入学生的分数为：" << score << endl;
    if (score <=  && score >= )
    {
        switch (score / )
        {
        case :;
        case :cout << "该学生成绩优异" << endl; break;
        case :;
        case :cout << "该学生成绩良好" << endl; break;
        case :cout << "该学生成绩及格" << endl; break;
        default:cout << "该学生成绩不及格，明年再战" << endl; break;

        }
    }
    else
        cout << "请重新输入正确的分数" << endl;

    system("pause");
    return ;

}