#include"Student.h" #include"StudentManager.h" #include<iostream> #include<fstream> #include<string> StudentManager::StudentManager(Student* s, int n) { this->n = n; student = new Student[n]; for (int i = 0; i < n; i++) { *(student + i) = *(s + i); } } void StudentManager::save() { ofstream outfile("StudentInfor.dat",ios_base::out|ios_base::binary); if (!outfile) { cout << "Failed to open file!" << endl; } for (int i = 0; i < n; i++) { outfile.write(reinterpret_cast<char*>(student + i), sizeof(*(student + i))); } outfile.close(); } void StudentManager::read() { delete[]student; student = new Student[n]; ifstream infile("StudentInfor.dat", ios_base::in | ios_base::binary); if (infile) { for (int i = 0; i < n; i++) { infile.read(reinterpret_cast<char*>(student + i), sizeof(*(student + i))); } } else { cout << "Failed to open file!" << endl; } infile.close(); for (int i = 0; i < n; i++) { cout << (student + i)->getNum() << "," << (student + i)->getName() << "," << (student + i)->getGender() << "," << (student + i)->getMath() << "," << (student + i)->getEnglish() << "," << (student + i)->getComputer() << "," << (student + i)->getAver() << endl; } }如何改进能避免读取访问权限冲突问题

可以将Student类中的私有成员变量改为protected类型，这样StudentManager类就可以直接访问这些成员变量，避免了访问权限冲突问题。同时，也可以将读取文件部分的代码封装到Student类中，让Student类自己负责从文件读取数据，这样也可以避免访问权限冲突问题。例如，在Student类中添加如下代码：

void readFromFile(ifstream& infile) {
    infile.read(reinterpret_cast<char*>(this), sizeof(*this));
}

然后，在StudentManager类的read()函数中调用这个函数：

if (infile) {
    for (int i = 0; i < n; i++) {
        (student + i)->readFromFile(infile);
    }
}

相关问题

用c++设计学生信息管理系统c++学生成绩管理系统有若干学生成绩记录组成，每个记录由学号、姓名、性别和成绩四部分组成，学号不超过11个字符，姓名不超过20个字符，性别为’m’(male)或’f’(female)，成绩为double型数据。该系统具有以下功能： ⑴程序开始执行时显示系统首界面及版权信息后，显示以下主菜单： *******学生成绩管理系统************* 1.添加学生成绩记录 2.显示学生成绩记录 3.查找学生成绩记录 4.删除学生成绩记录 5.保存学生成绩

记录 6.读取学生成绩记录 7.统计学生成绩信息 0.退出系统 ************************************ ⑵ 添加学生成绩记录：输入学生信息，程序自动生成唯一的学号，将学生信息添加到系统中。

⑶ 显示学生成绩记录：按学生学号、姓名、性别、成绩等方式查询并显示学生成绩记录。

⑷ 查找学生成绩记录：根据学号查询并显示学生信息。

⑸ 删除学生成绩记录：根据学号删除学生信息。

⑹ 保存学生成绩记录：将当前系统中学生信息保存到文件中。

⑺ 读取学生成绩记录：从文件中读取学生信息。

⑻ 统计学生成绩信息：统计系统中所有学生的总人数、平均成绩、最高分、最低分等信息。

⑼ 退出系统：程序结束执行。

以下是一个简单的 C++ 实现示例，仅供参考：

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

// 学生信息结构体
struct Student {
    string id; // 学号
    string name; // 姓名
    char gender; // 性别
    double score; // 成绩
};

// 学生信息管理类
class StudentManager {
private:
    vector<Student> students; // 学生信息列表
    int count; // 学生总人数
    double avgScore; // 平均成绩
    double maxScore; // 最高分
    double minScore; // 最低分

public:
    StudentManager() {
        count = 0;
        avgScore = 0;
        maxScore = 0;
        minScore = 100;
    }

    // 添加学生信息
    void addStudent() {
        Student student;
        cout << "请输入学生姓名：" << endl;
        cin >> student.name;
        cout << "请输入学生性别（m/f）：" << endl;
        cin >> student.gender;
        cout << "请输入学生成绩：" << endl;
        cin >> student.score;
        student.id = "S" + to_string(count + 1); // 自动生成学号
        students.push_back(student);
        count++;
        avgScore = (avgScore * (count - 1) + student.score) / count;
        maxScore = max(maxScore, student.score);
        minScore = min(minScore, student.score);
        cout << "添加成功！" << endl;
    }

    // 显示学生信息
    void showStudents() {
        if (students.empty()) {
            cout << "暂无学生信息！" << endl;
            return;
        }
        cout << "学号\t姓名\t性别\t成绩" << endl;
        for (auto s : students) {
            cout << s.id << "\t" << s.name << "\t" << s.gender << "\t" << s.score << endl;
        }
    }

    // 查找学生信息
    void searchStudent() {
        if (students.empty()) {
            cout << "暂无学生信息！" << endl;
            return;
        }
        string id;
        cout << "请输入要查找的学生学号：" << endl;
        cin >> id;
        for (auto s : students) {
            if (s.id == id) {
                cout << "学号\t姓名\t性别\t成绩" << endl;
                cout << s.id << "\t" << s.name << "\t" << s.gender << "\t" << s.score << endl;
                return;
            }
        }
        cout << "未找到该学生信息！" << endl;
    }

    // 删除学生信息
    void deleteStudent() {
        if (students.empty()) {
            cout << "暂无学生信息！" << endl;
            return;
        }
        string id;
        cout << "请输入要删除的学生学号：" << endl;
        cin >> id;
        for (auto it = students.begin(); it != students.end(); it++) {
            if (it->id == id) {
                avgScore = (avgScore * count - it->score) / (count - 1);
                count--;
                students.erase(it);
                cout << "删除成功！" << endl;
                return;
            }
        }
        cout << "未找到该学生信息！" << endl;
    }

    // 保存学生信息到文件
    void saveToFile() {
        if (students.empty()) {
            cout << "暂无学生信息！" << endl;
            return;
        }
        ofstream outFile("students.txt");
        for (auto s : students) {
            outFile << s.id << "," << s.name << "," << s.gender << "," << s.score << endl;
        }
        cout << "保存成功！" << endl;
    }

    // 从文件中读取学生信息
    void readFromFile() {
        ifstream inFile("students.txt");
        if (!inFile.is_open()) {
            cout << "文件不存在！" << endl;
            return;
        }
        string line;
        while (getline(inFile, line)) {
            Student student;
            int pos = line.find(",");
            student.id = line.substr(0, pos);
            line = line.substr(pos + 1);
            pos = line.find(",");
            student.name = line.substr(0, pos);
            line = line.substr(pos + 1);
            pos = line.find(",");
            student.gender = line[0];
            line = line.substr(pos + 1);
            student.score = stod(line);
            students.push_back(student);
            count++;
            avgScore = (avgScore * (count - 1) + student.score) / count;
            maxScore = max(maxScore, student.score);
            minScore = min(minScore, student.score);
        }
        cout << "读取成功！" << endl;
    }

    // 统计学生信息
    void statistics() {
        if (students.empty()) {
            cout << "暂无学生信息！" << endl;
            return;
        }
        cout << "学生总人数：" << count << endl;
        cout << "平均成绩：" << avgScore << endl;
        cout << "最高分：" << maxScore << endl;
        cout << "最低分：" << minScore << endl;
    }
};

int main() {
    StudentManager manager;
    int choice;
    while (true) {
        cout << "*******学生成绩管理系统*************" << endl;
        cout << "1.添加学生成绩记录" << endl;
        cout << "2.显示学生成绩记录" << endl;
        cout << "3.查找学生成绩记录" << endl;
        cout << "4.删除学生成绩记录" << endl;
        cout << "5.保存学生成绩记录" << endl;
        cout << "6.读取学生成绩记录" << endl;
        cout << "7.统计学生成绩信息" << endl;
        cout << "0.退出系统" << endl;
        cout << "************************************" << endl;
        cout << "请选择操作（0-7）：" << endl;
        cin >> choice;
        switch (choice) {
        case 1:
            manager.addStudent();
            break;
        case 2:
            manager.showStudents();
            break;
        case 3:
            manager.searchStudent();
            break;
        case 4:
            manager.deleteStudent();
            break;
        case 5:
            manager.saveToFile();
            break;
        case 6:
            manager.readFromFile();
            break;
        case 7:
            manager.statistics();
            break;
        case 0:
            cout << "谢谢使用！" << endl;
            return 0;
        default:
            cout << "输入有误，请重新输入！" << endl;
        }
    }
}

定义一个学生类, 包含学生的学号、 姓名和年龄等基本信息, 将学生信息写入二进 制文件 student. dat 中, 实现对学生信息的显示、 查询和删除等基本功能。用c++

下面是一个示例的学生类定义和实现：

#include <iostream>
#include <fstream>
#include <cstring>

using namespace std;

const int MAX_NAME_LEN = 20;

struct Student {
    int id;
    char name[MAX_NAME_LEN];
    int age;
};

class StudentManager {
public:
    void addStudent(int id, const char* name, int age);
    void displayAllStudents();
    void findStudentById(int id);
    void removeStudentById(int id);
private:
    fstream file;
    void writeStudentToFile(const Student& student);
    Student readStudentFromFile();
    bool matchById(const Student& student, int id);
};

void StudentManager::addStudent(int id, const char* name, int age) {
    Student student = {id};
    strncpy(student.name, name, MAX_NAME_LEN - 1);
    student.age = age;
    writeStudentToFile(student);
}

void StudentManager::displayAllStudents() {
    file.open("student.dat", ios::in | ios::binary);
    Student student;
    while (file.read(reinterpret_cast<char*>(&student), sizeof(Student))) {
        cout << "id: " << student.id << ", name: " << student.name << ", age: " << student.age << endl;
    }
    file.close();
}

void StudentManager::findStudentById(int id) {
    file.open("student.dat", ios::in | ios::binary);
    Student student;
    bool found = false;
    while (file.read(reinterpret_cast<char*>(&student), sizeof(Student))) {
        if (matchById(student, id)) {
            cout << "id: " << student.id << ", name: " << student.name << ", age: " << student.age << endl;
            found = true;
            break;
        }
    }
    if (!found) {
        cout << "Student with id " << id << " not found" << endl;
    }
    file.close();
}

void StudentManager::removeStudentById(int id) {
    file.open("student.dat", ios::in | ios::out | ios::binary);
    Student student;
    int pos = 0;
    while (file.read(reinterpret_cast<char*>(&student), sizeof(Student))) {
        if (matchById(student, id)) {
            file.seekp(pos);
            Student emptyStudent = {0};
            file.write(reinterpret_cast<char*>(&emptyStudent), sizeof(Student));
            cout << "Student with id " << id << " removed" << endl;
            break;
        }
        pos = file.tellg();
    }
    if (file.eof()) {
        cout << "Student with id " << id << " not found" << endl;
    }
    file.close();
}

void StudentManager::writeStudentToFile(const Student& student) {
    file.open("student.dat", ios::out | ios::app | ios::binary);
    file.write(reinterpret_cast<const char*>(&student), sizeof(Student));
    file.close();
}

Student StudentManager::readStudentFromFile() {
    Student student;
    file.read(reinterpret_cast<char*>(&student), sizeof(Student));
    return student;
}

bool StudentManager::matchById(const Student& student, int id) {
    return student.id == id;
}

在这个实现中，我们使用了 `fstream` 类来读写二进制文件。具体来说，对于写入操作，我们使用了 `ios::out` 和 `ios::app` 模式打开文件，以便在文件末尾添加新的学生信息；对于读取操作，我们使用了 `ios::in` 模式打开文件。在读写操作中，我们使用了 `reinterpret_cast` 来进行指针类型的转换，以便正确地读写二进制数据。

另外，我们还实现了一些基本的功能，比如添加学生、显示所有学生、按照学号查找学生和按照学号删除学生。在查找和删除操作中，我们使用了一个辅助函数 `matchById` 来判断学生信息是否与给定的学号匹配。

最后，我们可以在 `main` 函数中测试我们的实现：

int main() {
    StudentManager manager;
    manager.addStudent(1, "Alice", 20);
    manager.addStudent(2, "Bob", 21);
    manager.addStudent(3, "Charlie", 22);
    cout << "All students:" << endl;
    manager.displayAllStudents();
    cout << "Find student with id 2:" << endl;
    manager.findStudentById(2);
    cout << "Remove student with id 3:" << endl;
    manager.removeStudentById(3);
    cout << "All students after removal:" << endl;
    manager.displayAllStudents();
    return 0;
}

输出结果应该为：

All students:
id: 1, name: Alice, age: 20
id: 2, name: Bob, age: 21
id: 3, name: Charlie, age: 22
Find student with id 2:
id: 2, name: Bob, age: 21
Remove student with id 3:
Student with id 3 removed
All students after removal:
id: 1, name: Alice, age: 20
id: 2, name: Bob, age: 21