Problem Regarding QFile....!

[gunturrohith]

hi i am trying to copy data using QFile from multiple files to single file, i.e file A and file B data should be stored in file C
here is the sample code that i am using,
once please check the code below:

QFile readfile("/mnt/sysuser/Analog_srno");
        if(!readfile.open(QIODevice::ReadOnly | QIODevice::Text))
                qDebug("file read file not open");
 
        QFile dest("/mnt/sysuser/CardTest");
        if(!dest.open(QIODevice::Append | QIODevice::Text))
                qDebug("file dest file not open");
 
        if(readfile.readAll().isEmpty())
        {
                Enter_Cpuno();
        }
        else
        {
        QByteArray buffer;
        qDebug("entering into while");
        while(!(buffer=readfile.readAll()).isEmpty())
        {
           write.dest(buffer);
        }
        readfile.close();
        }
        QFile read_file("/mnt/sysuser/Cpu_srno");
        if(!read_file.open(QIODevice::ReadOnly | QIODevice::Text))
                qDebug("file read file not open");
 
        if(read_file.readAll().isEmpty())
        {
                Enter_Cpuno1();
        }
 
        else
        {
        QByteArray buffer;
        qDebug("entering into while");
        while(!(buffer=readfile.readAll()).isEmpty())
        {
           write.dest(buffer);
        }
        read_file.close();
        dest.close();
        }

QFile readfile("/mnt/sysuser/Analog_srno");
        if(!readfile.open(QIODevice::ReadOnly | QIODevice::Text))
                qDebug("file read file not open");

        QFile dest("/mnt/sysuser/CardTest");
        if(!dest.open(QIODevice::Append | QIODevice::Text))
                qDebug("file dest file not open");

        if(readfile.readAll().isEmpty())
        {
                Enter_Cpuno();
        }
        else
        {
        QByteArray buffer;
        qDebug("entering into while");
        while(!(buffer=readfile.readAll()).isEmpty())
        {
           write.dest(buffer);
        }
        readfile.close();
        }
        QFile read_file("/mnt/sysuser/Cpu_srno");
        if(!read_file.open(QIODevice::ReadOnly | QIODevice::Text))
                qDebug("file read file not open");

        if(read_file.readAll().isEmpty())
        {
                Enter_Cpuno1();
        }

        else
        {
        QByteArray buffer;
        qDebug("entering into while");
        while(!(buffer=readfile.readAll()).isEmpty())
        {
           write.dest(buffer);
        }
        read_file.close();
        dest.close();
        }

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I am using the version of QT-4.7.4 -Please notify me if there is an error ,
Please help/guide me,
thanks in advance,
rohith.g

[anda_skoa]

You call readAll() in your if() conditions. That reads all data from the file.

Assuming there was data, you enter the else part of your code, which then calls readAll() again.
Since the file is at the end already, the result is an empty byte array.

Better use QFile::size() to check if the file is not empty.

And you don't need to specify QIODevice::Text when opening, you are not interpreting the content in any way.

Cheers,
_