Creating writing into a new file in Qt

Question

I am trying to write into a file and if the file doesn t exist create it  I have searched on the internet and nothing worked for me   My code looks currently like this   QString filename  Data txt   QFile file  filename    if   file open QIODevice  ReadWrite          QTextStream stream   amp file        stream  lt  lt   something   lt  lt  endl      If I create a text file called Data in the directory  it remains empty  If I don t create anything it doesn t create the file either  I don t know what to do with this  this isn t the first way in which I tried to create write into a file and none of the ways worked   Thanks for your answers

User · Accepted Answer

Are you sure you re in the right directory  Opening a file without a full path will open it in the current working directory  In most cases this is not what you want  Try changing the first line to   QString filename  c   Data txt  or QString filename  c  Data txt   and see if the file is created in c

User · Answer

It can happen that the cause is not that you don t find the right directory  For example  you can read from the file  even without absolute path  but it seems you cannot write into it   In that case  it might be that you program exits before the writing can be finished   If your program uses an event loop  like with a GUI application  e g  QMainWindow  it s not a problem  However  if your program exits immediately after writing to the file  you should flush the text stream  closing the file is not always enough  and it s unnecessary  as it is closed in the destructor    stream  lt  lt   something   lt  lt  endl  stream flush      This guarantees that the changes are committed to the file before the program continues from this instruction    The problem seems to be that the QFile is destructed before the QTextStream  So  even if the stream is flushed in the QTextStream destructor  it s too late  as the file is already closed

User · Answer

That is weird  everything looks fine  are you sure it does not work for you  Because this main surely works for me  so I would look somewhere else for the source of your problem    include  lt QFile gt   include  lt QTextStream gt    int main         QString filename    Data txt       QFile file filename       if  file open QIODevice  ReadWrite             QTextStream stream  amp file           stream  lt  lt   something   lt  lt  endl            The code you provided is also almost the same as the one provided in detailed description of QTextStream so I am pretty sure  that the problem is elsewhere     Also note  that the file is not called Data but Data txt and should be created located in the directory from which the program was run  not necessarily the one where the executable is located

User · Answer

Your code is perfectly fine  you are just not looking at the right location to find your file  Since you haven t provided absolute path  your file will be created relative to the current working folder  more precisely in the current working folder in your case    Your current working folder is set by Qt Creator  Go to Projects    Your selected build    Press the  Run  button  next to  Build  and you will see what it is on this page which of course you can change as well

User · Answer

QFile file  test txt         If file does not exist  it will be created     if   file open QIODevice  ReadOnly   QIODevice  Text   QIODevice  ReadWrite         qDebug    lt  lt   FAILED TO CREATE FILE   FILE DOES NOT EXIST        for Reading line by line from text file   while   file atEnd          QByteArray line   file readLine        qDebug    lt  lt   read output -    lt  lt  line       for writing line by line to text file    if  file open QIODevice  ReadWrite         QTextStream stream  amp file       stream  lt  lt   1 XYZ  lt  lt endl      stream  lt  lt   2 XYZ  lt  lt endl

User · Answer

include  lt QFile gt   include  lt QCoreApplication gt   include  lt QTextStream gt   int main int argc  char  argv             Create a new file          QFile file  out txt        file open QIODevice  WriteOnly   QIODevice  Text       QTextStream out  amp file       out  lt  lt   This file is generated by Qt n           optional  as QFile destructor will already do it      file close            this would normally start the event loop  but is not needed for this       minimal example        return app exec         return 0

[c++] Creating/writing into a new file in Qt

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