C++无法将学生信息以正确文本格式写入文件的技术求助

编写的C++学生信息管理程序，期望将学生的姓名（name）、学号（roll）、百分比（per）以可读的文本格式写入student.txt文件，但当前代码使用f.write()写入整个student对象，导致文件内容为二进制格式（显示乱码）。

原代码如下：

#include<iostream>
#include<fstream>

using namespace std;

class student
{  
    string name;
    int roll;
    float per;

  public:
    void put()
    {
        cout << "Name: " << name << endl;
        cout << "Roll no.: " << roll << endl;
        cout << "Percentage: " << per << endl;
        cout << endl;
    }
    void get()
    {
        cout << "Enter your name: ";
        cin >> name;
        cout << "Enter your roll no.: ";
        cin >> roll;
        cout << "Enter your percentage: ";
        cin >> per;
        cout << endl;
    }
};

int main()
{
    student s;
    fstream f;

    int ch;
    while(1)
        {
         cout<<"\n-------------------MENU-------------------\n";
         cout<<"1.Add Record\n";
         cout<<"2.Search\n";
         cout<<"3.Delete\n";
         cout<<"4.Modify\n";
         cout<<"5.Display File\n";
         cout<<"6.QUIT\n";

        cout << "\nEnter your choice: ";
        cin>>ch;
    
            switch(ch)
            {
             case 1:
                    f.open("student.txt", ios::app);
                    s.get();
                    f.write((char*)&s, sizeof(s));
                    f.close();
                    break;
                        
             case 5:
                    f.open("student.txt", ios::in);
                    while (f.eof() != 0)
                    {
                        f.read((char*)&s, sizeof(s));
                        s.put();
                    }
                    f.close();
                    break;
    
             case 6: cout << "Quiting\n";
                    return -1;
    
            default: cout << "Invalid input";
            }
        }   

    return 0;
}

要实现可读文本格式的写入和读取，需要替换二进制读写的f.write()和f.read()，改用文本流操作（类似cout和cin的方式），同时为student类添加文本读写的成员函数以保证封装性。

具体修改点：

• 新增writeToFile成员函数，将学生信息按文本格式写入文件流
• 新增readFromFile成员函数，从文本文件流读取数据并初始化对象
• 修改主函数中添加记录和显示文件的逻辑，替换二进制读写为文本读写
• 修复文件读取时的结束判断逻辑，避免重复输出最后一条记录

修改后的代码：

#include<iostream>
#include<fstream>
#include<string>

using namespace std;

class student
{  
    string name;
    int roll;
    float per;

  public:
    void put()
    {
        cout << "Name: " << name << endl;
        cout << "Roll no.: " << roll << endl;
        cout << "Percentage: " << per << endl;
        cout << endl;
    }
    void get()
    {
        cout << "Enter your name: ";
        cin >> name;
        cout << "Enter your roll no.: ";
        cin >> roll;
        cout << "Enter your percentage: ";
        cin >> per;
        cout << endl;
    }

    // 将学生信息以文本格式写入文件流
    void writeToFile(ofstream& out) const
    {
        out << name << " " << roll << " " << per << endl;
    }

    // 从文件流读取文本格式的学生信息，读取失败返回false
    bool readFromFile(ifstream& in)
    {
        return in >> name >> roll >> per;
    }
};

int main()
{
    student s;

    int ch;
    while(1)
        {
         cout<<"\n-------------------MENU-------------------\n";
         cout<<"1.Add Record\n";
         cout<<"2.Search\n";
         cout<<"3.Delete\n";
         cout<<"4.Modify\n";
         cout<<"5.Display File\n";
         cout<<"6.QUIT\n";

        cout << "\nEnter your choice: ";
        cin>>ch;
    
            switch(ch)
            {
             case 1:
                    ofstream outFile("student.txt", ios::app);
                    s.get();
                    s.writeToFile(outFile);
                    outFile.close();
                    break;
                        
             case 5:
                    ifstream inFile("student.txt");
                    while (s.readFromFile(inFile))
                    {
                        s.put();
                    }
                    inFile.close();
                    break;
    
             case 6: cout << "Quiting\n";
                    return 0;
    
            default: cout << "Invalid input\n";
            }
        }   

    return 0;
}

• 修改后student.txt中每一行对应一个学生的信息，格式为姓名 学号 百分比，例如Alice 101 92.5，完全可读
• readFromFile通过返回值判断读取状态，解决了原代码中while(f.eof() !=0)导致的重复读取问题
• 使用ofstream和ifstream分别处理写入和读取，逻辑更清晰

内容的提问来源于stack exchange，提问作者Akshay