下面这段代码要实现对学生对象按照成绩降序排序。 仔细阅读代码，要求实现编程实现输出运算符“<<”和小于“<”运算符，使本程序能完成预定的排序功能。 裁判测试程序样例： #include <iostream> #include <string> #include <list> using namespace std; class Student { string name; char sex; int score; string grade; public: Student(string name, char sex, int score, string grade); friend ostream &operator<< (ostream& os, Student st) ; friend bool operator<(Student &st1, Student &st2); }; //你提交的代码将被嵌入到这里 Student::Student(string name, char sex, int score, string grade) { this->name = name; this->sex = sex; this->score = score; this->grade = grade; } int main() { list<Student> st; string name, grade; char sex; int score; for(int i = 0; i < 5; i++) { cin>>name; cin>>sex; cin>>score; cin>>grade; st.push_back(Student(name, sex, score, grade)); } st.sort(); list<Student>::iterator p = st.begin(); while(p != st.end()) { cout<<*p; p++; } return 0; } 输入样例： 在这里给出一组输入。例如： Bill M 86 JK1501 David M 98 JK1502 Mary F 78 JK1503 Adam M 83 JK1504 Rose F 96 JK1505 输出样例： 在这里给出相应的输出。例如： David M 98 JK1502 Rose F 96 JK1505 Bill M 86 JK1501 Adam M 83 JK1504 Mary F 78 JK1503

以下是实现了输出运算符“<<”和小于“<”运算符的代码：

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

class Student {
    string name;
    char sex;
    int score;
    string grade;
public:
    Student(string name, char sex, int score, string grade);
    friend ostream &operator<< (ostream& os, Student st);
    friend bool operator<(Student &st1, Student &st2);
};

Student::Student(string name, char sex, int score, string grade) {
    this->name = name;
    this->sex = sex;
    this->score = score;
    this->grade = grade;
}

ostream &operator<< (ostream& os, Student st) {
    os << st.name << " " << st.sex << " " << st.score << " " << st.grade << endl;
    return os;
}

bool operator<(Student &st1, Student &st2) {
    return st1.score > st2.score;
}

int main() {
    list<Student> st;
    string name, grade;
    char sex;
    int score;

    for(int i = 0; i < 5; i++) {
        cin >> name;
        cin >> sex;
        cin >> score;
        cin >> grade;
        st.push_back(Student(name, sex, score, grade));
    }

    st.sort();

    list<Student>::iterator p = st.begin();
    while(p != st.end()) {
        cout << *p;
        p++;
    }

    return 0;
}

在上面的代码中，我们重载了输出运算符“<<”和小于“<”运算符，分别用来输出学生信息和比较学生成绩。在主函数中，我们通过list容器存储学生对象，并使用sort函数来进行排序，最后输出排序后的结果。