delete a line from a file [was:Heeeeeelp please!!!!]

[anirban ghosh]

How can i delete a line from a file created using a C++ program?Can i get a code sample please? I am in desperate need of it!!!
I need it because i am writing a dbms project where i need to delete a line from a dat file. I have done the following but its not working!!I have posted it earlier but i did not get any sure answer. Please help!!!!

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ofstream fout("file.dat",ios::out);
    fout << "Sunanda 5 \n";
    fout << "Rahool 10 \n";
    fout << "Sunetra 12 \n";
    fout.close();
    
    ofstream fapp("file.dat",ios::out);
    fapp.seekp(23);
    int i = 0;
    while(i < 11)
    {
            fapp << '\b';
            i++;
    }        
    fapp.close();
    system("pause");                   
}

[drkybelk]

Hi,

I don't think you can do that. I suggest you read in your file and write everything but the line you want to delete to a temporary file and then rename the temporary file to your original file. It's not very efficient, but it'll work. Alternatively you can open your file as read/write and overwrite the line you want to delete with the rest of the file...

Cheers,

Dieter

[Danny]

In standard C++ it's quite diffciult to do this because you will need to isntrcut the file syetm that the file's size has changed. A simpler solution is to read teh file into a memory buffer, manipulate it, and then rewrite the whole buffer into the original file, overwriting the previous content.