C++用类和文件实现学生记录处理程序

好的，以下是一个可能的实现：

### 学生类

// student.h

#ifndef STUDENT_H
#define STUDENT_H

#include <string>

class Student {
public:
    Student();
    Student(const std::string& name, int id, double gpa);
    ~Student();

    // getters
    std::string getName() const;
    int getId() const;
    double getGpa() const;

    // setters
    void setName(const std::string& name);
    void setId(int id);
    void setGpa(double gpa);

    // file I/O
    void writeToFile(std::ofstream& file) const;
    void readFromFile(std::ifstream& file);

private:
    std::string m_name;
    int m_id;
    double m_gpa;
};

#endif // STUDENT_H

// student.cpp

#include "student.h"
#include <iostream>

Student::Student() : m_name(""), m_id(0), m_gpa(0.0) {}

Student::Student(const std::string& name, int id, double gpa) :
    m_name(name), m_id(id), m_gpa(gpa) {}

Student::~Student() {}

std::string Student::getName() const {
    return m_name;
}

int Student::getId() const {
    return m_id;
}

double Student::getGpa() const {
    return m_gpa;
}

void Student::setName(const std::string& name) {
    m_name = name;
}

void Student::setId(int id) {
    m_id = id;
}

void Student::setGpa(double gpa) {
    m_gpa = gpa;
}

void Student::writeToFile(std::ofstream& file) const {
    file << m_name << " " << m_id << " " << m_gpa << std::endl;
}

void Student::readFromFile(std::ifstream& file) {
    file >> m_name >> m_id >> m_gpa;
}

### 主程序

#include <iostream>
#include <fstream>
#include "student.h"

const std::string FILENAME = "students.txt";

void addStudent(std::ofstream& file) {
    std::string name;
    int id;
    double gpa;

    std::cout << "Enter name: ";
    std::getline(std::cin, name);

    std::cout << "Enter ID: ";
    std::cin >> id;

    std::cout << "Enter GPA: ";
    std::cin >> gpa;

    Student student(name, id, gpa);
    student.writeToFile(file);

    std::cout << "Student added." << std::endl;
}

void printRecords(std::ifstream& file) {
    Student student;
    while (!file.eof()) {
        student.readFromFile(file);
        std::cout << "Name: " << student.getName() << std::endl;
        std::cout << "ID: " << student.getId() << std::endl;
        std::cout << "GPA: " << student.getGpa() << std::endl;
        std::cout << std::endl;
    }
}

int main() {
    std::ofstream outfile(FILENAME, std::ios::app);
    if (!outfile) {
        std::cerr << "Failed to open file for writing." << std::endl;
        return 1;
    }

    std::ifstream infile(FILENAME);
    if (!infile) {
        std::cerr << "Failed to open file for reading." << std::endl;
        return 1;
    }

    int choice;
    do {
        std::cout << "1. Add student" << std::endl;
        std::cout << "2. Print records" << std::endl;
        std::cout << "0. Exit" << std::endl;
        std::cout << "Enter choice: ";
        std::cin >> choice;

        switch (choice) {
            case 1:
                addStudent(outfile);
                break;
            case 2:
                printRecords(infile);
                break;
            case 0:
                std::cout << "Goodbye!" << std::endl;
                break;
            default:
                std::cout << "Invalid choice." << std::endl;
                break;
        }

    } while (choice != 0);

    outfile.close();
    infile.close();

    return 0;
}

这个程序可以让用户添加学生记录到文件中，并在需要时从文件中打印学生记录。在这个实现中，文件是永久性存储的，学生记录在程序启动时从文件中读入，并在程序退出时写入文件。