Opening an existing text file erases its contents altogether

I am trying to open a text file in C++ (it has content). Every time I open, it ends up erasing the contents of the file altogether, which I do not want.

#include <fstream>
#include <iostream>

using namespace std;

int main() {
    string filename;
    cout << "Enter File name : ";
    cin >> filename;
    fstream file;
    file.open(filename, fstream::out);
    file.close();
    return 0;
}

}

>Solution :

Instead of fstream::out which discards everything which was previously present in the file, you should use fstream::app which will not delete the contents of the file and continue writing to it from its end.

From cppreference: