Thread: fstream confusion

My objective is to write to a file and read it back. All the reading is done after all the writing.

Code:

// first version
ofstream outFile("file.txt", ios::binary | ios::out | ios::in);
ifstream inFile("file.txt", ios::binary | ios::in);

With codes above, file.txt is not created when I run it.

Code:

// second version
ofstream outFile("studentVer1.txt", ios::binary | ios::out);
ifstream inFile("studentVer1.txt", ios::binary | ios::in);

With these ones, file.txt is created but reading is unsuccessful.

When I do first version and create a blank file.txt, first run will write but fail to read, second run and after will write and read.

So, whatsupp??

I did this

Code:

fstream file("file.txt", ios::binary | ios::out | ios::in);

and after each writing I followed by

Code:

file.flush();

and right before I started reading

Code:

file.seekg(0);

But...still no file.txt is created, and if I create blank file.txt, it will write and read fine. Any suspicion?
Anybody has the same case before? I'm afraid that some other codes in my program that cause it, but it's a lot of codes to post. So, any suggestion what to check?

To create a file if it doesn't exist, not overwrite the data in the file if it does exist, and start at the beginning of the file then you can try this:

ofstream fout(filename, ios::in | ios:ut | ios::trunc);

I'm not sure it does all that, but I think it does, and it won't hurt to try on a sample file. Alternatively look for existense first, create the file second if need be.

Code:

ofstrean fout;
ifstream fin(filename);
if(!fin.is_open())
{
  fout.open(filename);
}
else
{
  fin.close();
  fout.open(filename, ios::in | ios::out);
}

Using an fstream may be a little easier.

Yup, weird, but that's the way I understand it.