C fstream write with overloaded "<<",but failed, file is still empty-CodePudding

#include <iostream>
#include <fstream>
#include <string.h>
#include <cstdlib>
#include <ctype.h>
#include <stdlib.h>
using namespace std;

class W_File_of_Int : public ofstream {
private:
    ofstream _fout;

public:
    W_File_of_Int(const char* nom_fic)
    {
        ofstream _fout(nom_fic, ios::out | ios::binary);
        cout << "\n\tfile of int to write is ready";
    }
    ~W_File_of_Int()
    {
        cout << "\n\tDestruction of file to write\n";
        _fout.close();
    }
    int tellp() { return ofstream::tellp(); }
    W_File_of_Int& operator<<(int i)
    {
        _fout.write((char*)&i, sizeof(int));
        return *this;
    }
};

int main()
{
    W_File_of_Int f_out("essai.fic");

    if (!f_out) {
        cerr << "\nErreur dansla creation de 'essai.fic'\n";
        return 1;
    }
    for (int i = 0; i <= 10; i  ) // Ecriture de 11 entiers dans le fichier
        f_out << i;
    cout << f_out.tellp() << "\n\telements sont ecrits dans le fichier.\n";
    // affiche: 11 elements sont ecrits dans le fichier.
    f_out.close();

    return 0;
}

I tried many times ,like make int to &int,it just don`t work

write with overloaded "<<",but failed, file is still empty.

CodePudding user response：

Your constructor has access to 3 different ofstream instances:

The base class
The member variable this->_fout
The local variable _fout.

You should probably use the base class only, for which you would need to change the constructor:

W_File_of_Int(const char* nom_fic) :
    ofstream(nom_fic, ios::out|ios::binary) // call base class constructor
{
    cout << "\n\tfile of int to write is ready";
}

CodePudding user response：

class W_File_of_Int :  public ofstream
{
private:ofstream _fout;
.......

here you create two ofstream : _fout AND the base class;

you should choose one