Read from File :: Help required

[abghosh]

Hi

I have file containing 1 GB of data. But I have to read only the last 1000 data from the file.
How can I go for it? Reading the entire file takes more than 15 minutes.

Thanks for any help.

[Lesiok]

Read about QFile::seek (http://doc.trolltech.com/4.6/qfile.html#seek) and QFile::size (http://doc.trolltech.com/4.6/qfile.html#size)

[abghosh]

Read about QFile::seek (http://doc.trolltech.com/4.6/qfile.html#seek) and QFile::size (http://doc.trolltech.com/4.6/qfile.html#size)

Hi Lesiok
Thanks for your help. But for using these functions I have to first know the number of lines in the file.
How can I get the number of lines in the file in one command?

[JohannesMunk]

Lines? 1 GB TextFile??

Otherwise QFile::size is really all you need.

If by lines you mean records of a given size, you can seek to QFile::size() - recordsize*1000 ...

Johannes

[Lesiok]

If lines have non const length the problem is not trivial.

[abghosh]

If lines have non const length the problem is not trivial.

Line sizes varies. Otherwise it would have been simple to multiply number of lines by each line size & subtract it from total file size.

In such case how can I do it?

[Lesiok]

Only reading all file. I think that it is time to change a philosophy. 1 GB text file it is not good idea.