DevC++ ios::app not working

[Jackhenry]

Hi, I'm kind of new to C++ programing but I'm facing a major problem.

I'm trying to append a file using ios::app in DevC++, but it just turncates the whole file when opened in any mode

Supposed the file contains:

This is a text file.



And say i wrote this code

void main()
{
    ofstream fout("File.txt",ios::app);
    getch();
}

and when I open the file after this, the contents of the file is completly erased.

Can anyone tell me what's going on?

[jlb]

Are you sure that the file contained data before you ran the program? Using the std::ios::app flag should preserve the file contents.

[Jackhenry]

100% sure. I had written a list of names. All gone when I opened in ios::app OR ios::ate

[Chervil]

It's hard to diagnose without a complete example to show the sequence of events.
Here's a simple example for test purposes:

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

using namespace std;

int main() 
{
    const char * fname = "File.txt";
    
    // 1. create a new file, write some text and close the file.
    {
        ofstream fout(fname);
        fout << "This is a text file.\n";
    }
    
    // 2. open the file in append mode, write some more text and close.
    {
        ofstream fout(fname, ios::app);  
        fout << "Oranges and lemons.\n";      
    }
    
    // 3. open the file for input and display the contents.   
    ifstream fin(fname);
    
    string line;
    while (getline(fin, line))
        cout << line << '\n';
        
    return 0;
}

Output:

This is a text file.
Oranges and lemons.

[Jackhenry]

@Chervil I had exactly tried that a day back! But it turncated the whole file.....

But today, It's doing fine......strange..

Anyways, thank you guys for helping me.