c++ - 如何在 C++ 中正确地将 vector 写入二进制文件？

Question

首先对不起我的英语不好。我刚加入这个论坛并搜索如何正确地将 vector 写入二进制文件。我刚从这个论坛得到一个这样的答案(我已经修改了一点):

#include <iostream>
#include <string.h>
#include <vector>
#include <fstream>

using namespace std;

class Student
{
public:
char m_name[30];
int m_score;

public:
Student()
{

}
Student(const char name[], const int &score)
:m_score(score)
{
    strcpy(m_name, name);
}
void print() const
{
    cout.setf(ios::left);
    cout.width(20);
    cout << m_name << " " << m_score << endl;
}
};


int main()
{
    vector<Student> student;
    student.push_back(Student("Alex",19));
    student.push_back(Student("Maria",20));
    student.push_back(Student("muhamed",20));
    student.push_back(Student("Jeniffer",20));
    student.push_back(Student("Alex",20));
    student.push_back(Student("Maria",21));

    ofstream fout("data.dat", ios::out | ios::binary);
    fout.write((char*) &student, sizeof(student));
    fout.close();

    vector<Student> student2;

    ifstream fin("data.dat", ios::in | ios::binary);
    fin.seekg(0, ifstream::end);
    int size = fin.tellg() / sizeof (student2);
    student2.resize(size);
    fin.seekg(0, ifstream::beg);
    fin.read((char*)&student2, sizeof(student2));
    vector<Student>::const_iterator itr = student2.begin();
    while(itr != student2.end())
    {
            itr->print();
            ++itr;
    }
    fin.close();
    return 0;
}

但是当我运行它时。在我的 linux mint 上，我得到了这个结果:

Alex                 19
Maria                20
muhamed              20
Jeniffer             20
Alex                 20
Maria                21
*** glibc detected *** ./from vector to binary: corrupted double-linked list: 0x0000000000633030 ***

我是 C++ 新手。有人请帮助我，过去两周一直陷入这个问题。提前感谢您的回答。

Answer 1

您正在写入 vector 结构文件，而不是其数据缓冲区。尝试将写入程序更改为:

 ofstream fout("data.dat", ios::out | ios::binary);
 fout.write((char*)&student[0], student.size() * sizeof(Student));
 fout.close();

而不是从文件大小计算 vector 的大小，最好先写 vector 大小(对象数)。在这种情况下，您可以将其他数据写入同一文件。

 size_t size = student.size();
 fout.write((char*)&size, sizeof(size));