Reading from a file in Qt

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hi i want to read a file in qt.
the file has around 2000 lines.
i want only 100 lines to be displayed at once.
i have put a next button.
on clicking this button next 100 lines must be displayed.
i am unable to go forward.
please help.
thanks in advance

Posted 14-Nov-11 21:04pm

Abhishek Durvasula

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Sergey Alexandrovich Kryukov 15-Nov-11 3:07am

What's the problem?
--SA

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elgaabeb · Answer 1 · 2011-11-14T23:14:00

Hi,

You must create a class that inherits from QFile with methods : - OpenFile() - ReadNextHundred() - CloseFile().
Then you connect ReadNextHundred() to the button "Next" Clicked Event.
Once button Clicked you should clear Display widget and show next lines.

I think that the example in this link would help you :
http://www.qtforum.org/article/34254/how-to-read-a-textfile-and-display-result-in-gui-qt-programming-problem.html[^]

Regards!

Sergey Alexandrovich Kryukov · Answer 2 · 2011-11-14T21:13:00

Look at the basic code samples here where readLine is used: http://lists.trolltech.com/qt-interest/2002-03/msg00576.html[^].

In your case, you should keep the file opened. Read 100 lines each time you request to forward a page.

Unfortunately, scrolling your view back would be more difficult, because all likes can have different length, so you don't know file position of each line before you read all previous lines. You would need to index your file by 100-line chunks on the fly on first read, keeping the results in a hash table of file positions indexed by chunk indexes. It is fairly simple but will require some thinking during implementation. :-)

—SA

Reading from a file in Qt

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