fstream ios:app troubles

I have searched through many pages and have yet to find an answer...

with
fstream myfile;

This snippet writes the line and works properly

myfile.open("test.txt", ios::out);
myfile << "This is my second entry.\n";
myfile.close();


This snippet erases everything in the file (it will not append)

myfile.open("test.txt", ios::app);
myfile << "This is my second entry.\n";
myfile.close();

I understood that fstream will let you use both ifstream and ofstream functions (including append) Why does this not work?

Code:

---

ofstream file("BLAH.txt",ios::app);

---

WOW! LOOK WHAT I FOUND!

http://www.cprogramming.com/tutorial/lesson10.html

Here is the whole program -

Code:

---

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

int main()
{

   
    char buffer[256];
    fstream myfile;
   
    myfile.open("test.txt", ios::out);
    myfile << "This is my first entry.\n";
    myfile.close();
   
    myfile.open("test.txt",ios::in);
    myfile.getline(buffer,100);
    cout << "The file originally contained:  " << buffer << "\n";
    myfile.close();
   
    myfile.open("test.txt", ios::app);// <--- There it is!!!
    myfile << "This is my second entry.\n";
    myfile.close();
   
   
    myfile.open("test.txt",ios::in);
    myfile.getline(buffer,100);
    cout << "The file now contains:  " << buffer << "\n";
    myfile.close();
   
    myfile.open("test.txt", ios::out);
    myfile << "This is my third entry.\n";
    myfile.close();
   
    myfile.open("test.txt",ios::in);
    myfile.getline(buffer,100);
    cout << "The file now contains:  " << buffer << "\n";
    myfile.close();
 
return 0;
}

---

Why, exactly, will ios::in ios::out work, but ios::app wil not?

Let me restate, I don't think I can use a real ofstream now (to append), because myfile is already declared as a type fstream. The compiler won't let me cross use them.

Ifstream is used for reading in files, ofstream is used to create them. You need to change your code, and read the link I gave you.

Maybe I am just daft. The post you linked does not help. I am not using ifstream and ofstream... I am using fstream.

The documentation that I am using says that:

when "myfile" is declared as type "fstream" you are able to:

myfile.open("whatever.txt",ios::in);
myfile.open("whatever.txt",ios::out);
myfile.open("whatever.txt",ios::trunc);
myfile.open("whatever.txt",ios::app);

You see, I cant simply ofstream now, becuase "myfile" is of type fstream...

Why do all the above examples work except the :app one?

I understand it's of type fstream. So just change it to 'ofstream' and it will work. Follow the link, unless you have to do it using fstream. I've never used fstream, so I can't help with that, ofstream always worked just fine for me.

Thank you much for your help. A very funny thing happened...


when I changed:
myfile.open("test.txt", ios::app);

to:
myfile.open("test.txt", ios::out|ios::app);

it started working. This completely wrecks me, as I can't see why. If I just use out, it erases everything else. If I just use app, it does nothing at all. When I use them both with an "|" it works.

Again, thanks much. I am such a noob.