newbie question: why QT specific file IO classes instead of generic c++ methods?

Bubu 0

Hi
I just started with Qt and the first tutorial: Text Finder. Why is QFile used instead some generic c++ classes for file I/O?

void TextFinder::loadTextFile()
{
    QFile inputFile(":/input.txt");
    inputFile.open(QIODevice::ReadOnly);

    QTextStream in(&inputFile);
    QString line = in.readAll();
    inputFile.close();

    ui->textEdit->setPlainText(line);
    QTextCursor cursor = ui->textEdit->textCursor();
    cursor.movePosition(QTextCursor::Start, QTextCursor::MoveAnchor, 1);
}

JonB

@Bubu-0
Because Qt is a framework, with lots & lots of classes/functions of its own. Offering different functionality compared to "generic c++ classes for file I/O".

There are lots of classes like this you come across in Qt, e.g. QString instead of std::string etc.

VRonin

QFile internally uses those native methods (see https://code.woboq.org/qt5/qtbase/src/corelib/io/qfsfileengine_unix.cpp.html#214 usinf fread) but takes away a lot of the overhead like managing file flags on unix and handling errors

wrosecrans

@Bubu-0 said in newbie question: why QT specific file IO classes instead of generic c++ methods?:

QFile inputFile(":/input.txt");

If you use Qt's resource system (file path starts with ":" ) to access files that are baked into the executable, Qt's file API's are the only thing that will do it.

If you just want to access a file on the disk, you can use whatever you want. But obviously the Qt tutorials are going to be tutorials in the Qt API's, not generic C++ lessons.