Issue with QT/using pointers of ifstream-like variables

[hyperfine]

Hello,

EDIT: I know that QT users are only a very small subset of the forum-goers here, so in reading this post I think it's ok to consider the QT specific terms as compatible with regular C++ terms, i.e., a QString is essentially the same as a std::string. I have tried to identify these similarities in my post.

I'm trying to write a program in QT. In order to read in data from a file, something like this is typically done in the following way:

QString linecontents;
QString InputFile = "/home/file";   //QString is essentially a regular string
QFile InputFile_f(InputFile);         //This is the file to be opened
InputFile_f->open(QIODevice::ReadOnly);      //This opens the file
QTextStream InputStream(InputFile);    //This creates a text stream for the opened file
while( !InputFile_f.atEnd() )                //.atEnd() is like <iostream>'s .eof()
   {
      linecontents = InputStream.readLine();
      //Do other stuff...
   }

Now, this is basically what I want to do. However, the issue is that creating a QFile object means that you must initialize it with the QString that is the file name (line 3 above). When my program is initialized, there is no file location because the user hasn't chosen which file he wants to open yet. Similarly, the QTextStream cannot be created yet because the QFile is incomplete (line 5 above).

My solution was to create initially just a pointer to a QFile object, and similarly a pointer to QTextStream. Then, whenever the user chooses the file they wish to open, I can create a QFile object and assign my pointer to that QFile, like so:

class File
{
   QString InputFile;
   QFile* InputFile_f;
   QTextStream* InputStream;

   void OpenFile();
};

void File::OpenFile()   //This function is called after user chooses file
{
    QString linecontents;
    InputFile_f = new QFile(InputFile);
    InputFile_f->open(QIODevice::ReadOnly);
    InputStream = new QTextStream(InputFile_f);
    while( !InputFile_f.atEnd() )
   {
      linecontents = InputStream.readLine();
   }
}

The problem is that the above function doesn't work; the QTextStream only reads the first line of my file and then stops, essentially indicating that it has reached the end of the file.

Now, in my mind everything I've done should work perfectly. However, months of programming have humbled me and I know that my logic must be incorrect. Can someone tell me what is wrong? I assume (and internet searches have hinted) that the problem lies with my pointers to QFile and QTextStream, and my usage of new.

I'm basically looking for someone to tell me why what I've done is incorrect, and also to recommend a change so that I can implement the program as I've described above.

Thanks!

[norm b]

You're reading the stream not the file so you should be using QTextStream::atEnd()

[hyperfine]

Wow, that fixed it. Thanks!