在上述代码的基础上，增加以下功能： 能够按任意一门课程的成绩，对学生信息进行排序； 能够将排序的结果写入到文件(students.txt)中； 程序启动时，能够自动从文件(students.txt)中的读取学生的信息 不省略代码 写出全部

好的，以下是对应的代码实现：

1. 按任意一门课程的成绩，对学生信息进行排序

struct Student {
    int id;
    int scores[5];
    double avgScore;
};

bool cmp(const Student& a, const Student& b, int course) {
    return a.scores[course - 1] > b.scores[course - 1];
}

void sortStudents(Student students[], int size, int course) {
    for (int i = 0; i < size - 1; i++) {
        for (int j = 0; j < size - i - 1; j++) {
            if (cmp(students[j], students[j + 1], course)) {
                Student temp = students[j];
                students[j] = students[j + 1];
                students[j + 1] = temp;
            }
        }
    }
}

2. 将排序的结果写入到文件(students.txt)中

void writeStudentsToFile(Student students[], int size, const char* filename) {
    ofstream outfile(filename);
    if (!outfile.is_open()) {
        cout << "Error opening file!" << endl;
        return;
    }
    for (int i = 0; i < size; i++) {
        outfile << students[i].id << " ";
        for (int j = 0; j < 5; j++) {
            outfile << students[i].scores[j] << " ";
        }
        outfile << students[i].avgScore << endl;
    }
    outfile.close();
}

3. 程序启动时，能够自动从文件(students.txt)中读取学生的信息

void readStudentsFromFile(Student students[], int& size, const char* filename) {
    ifstream infile(filename);
    if (!infile.is_open()) {
        cout << "Error opening file!" << endl;
        return;
    }
    int id, score;
    while (infile >> id) {
        students[size].id = id;
        double sum = 0;
        for (int i = 0; i < 5; i++) {
            infile >> score;
            students[size].scores[i] = score;
            sum += score;
        }
        students[size].avgScore = sum / 5.0;
        size++;
    }
    infile.close();
}

完整代码如下：