#include <iostream> #include <fstream> #include <algorithm> using namespace std; struct Student { int id; string name; string className; double score1, score2, score3; double average; }; bool cmp(Student a, Student b) { return a.average > b.average; //按照平均成绩从高到低排序 } int main() { Student students[3]; //输入学生信息 for (int i = 0; i < 3; i++) { cout << "请输入第" << i+1 << "名学生的学号、姓名、班级信息、3门课程成绩（用空格隔开）：" << endl; cin >> students[i].id >> students[i].name >> students[i].className >> students[i].score1 >> students[i].score2 >> students[i].score3; students[i].average = (students[i].score1 + students[i].score2 + students[i].score3) / 3; } //将学生信息输出到文件f1中 ofstream fout1("f1.txt"); if (!fout1) { cout << "文件打开失败！" << endl; return 0; } for (int i = 0; i < 3; i++) { fout1 << students[i].id << " " << students[i].name << " " << students[i].className << " "; fout1 << students[i].score1 << " " << students[i].score2 << " " << students[i].score3 << " "; fout1 << students[i].average << endl; } fout1.close(); //按照平均成绩从高到低排序 sort(students, students+3, cmp); //将学生信息输出到文件f2中 ofstream fout2("f2.txt"); if (!fout2) { cout << "文件打开失败！" << endl; return 0; } for (int i = 0; i < 3; i++) { fout2 << students[i].id << " " << students[i].name << " " << students[i].className << " "; fout2 << students[i].score1 << " " << students[i].score2 << " " << students[i].score3 << " "; fout2 << students[i].average << endl; } fout2.close(); cout << "学生信息已经成功输出到文件f1和f2中！" << endl; return 0; } 基于这个案例简单加其他功能或者改写，写出改写后的完整代码

以下是改写后的完整代码，增加了从文件中读取学生信息和显示学生信息的功能：

#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

struct Student {
    int id;
    string name;
    string className;
    double score1, score2, score3;
    double average;
};

bool cmp(Student a, Student b) {
    return a.average > b.average; //按照平均成绩从高到低排序
}

void inputStudentInfo(Student students[]) {
    //输入学生信息
    for (int i = 0; i < 3; i++) {
        cout << "请输入第" << i+1 << "名学生的学号、姓名、班级信息、3门课程成绩（用空格隔开）：" << endl;
        cin >> students[i].id >> students[i].name >> students[i].className >> students[i].score1 >> students[i].score2 >> students[i].score3;
        students[i].average = (students[i].score1 + students[i].score2 + students[i].score3) / 3;
    }
}

void outputStudentInfo(ofstream& fout, Student students[]) {
    //将学生信息输出到文件中
    if (!fout) {
        cout << "文件打开失败！" << endl;
        return;
    }
    for (int i = 0; i < 3; i++) {
        fout << students[i].id << " " << students[i].name << " " << students[i].className << " ";
        fout << students[i].score1 << " " << students[i].score2 << " " << students[i].score3 << " ";
        fout << students[i].average << endl;
    }
    fout.close();
    cout << "学生信息已经成功输出到文件中！" << endl;
}

void readStudentInfo(ifstream& fin, Student students[]) {
    //从文件中读取学生信息
    if (!fin) {
        cout << "文件打开失败！" << endl;
        return;
    }
    for (int i = 0; i < 3; i++) {
        fin >> students[i].id >> students[i].name >> students[i].className >> students[i].score1 >> students[i].score2 >> students[i].score3;
        students[i].average = (students[i].score1 + students[i].score2 + students[i].score3) / 3;
    }
    fin.close();
    cout << "学生信息已经成功从文件中读取！" << endl;
}

void displayStudentInfo(Student students[]) {
    //显示学生信息
    cout << "学号\t姓名\t班级\t成绩1\t成绩2\t成绩3\t平均成绩" << endl;
    for (int i = 0; i < 3; i++) {
        cout << students[i].id << "\t" << students[i].name << "\t" << students[i].className << "\t";
        cout << students[i].score1 << "\t" << students[i].score2 << "\t" << students[i].score3 << "\t";
        cout << students[i].average << endl;
    }
}

int main() {
    Student students[3];

    //输入学生信息并输出到文件f1中
    inputStudentInfo(students);
    ofstream fout1("f1.txt");
    outputStudentInfo(fout1, students);

    //从文件f1中读取学生信息并按照平均成绩从高到低排序，然后输出到文件f2中
    ifstream fin("f1.txt");
    readStudentInfo(fin, students);
    sort(students, students+3, cmp);
    ofstream fout2("f2.txt");
    outputStudentInfo(fout2, students);

    //显示学生信息
    displayStudentInfo(students);

    return 0;
}