reading a writing to a text file

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Azza
Azza 2012-6-12
Hi,
I have a large textfile and ~ 3GB and I want to select only certain lines and save these lines in a new file. I am reading the files in chunks and for each chunk of data I want to choose the lines that I want and write them into the new file, then go back and read another chunk and so on until I reach the end of file. I have tried to save these lines in the new file by opening a new file using fopen 'w' and fprint my lines and then closing the file using fclose for each chunk of data that I read . However, I found that my data gets deleted in each fopen and fclose. I was wondering if there is an efficient way for the lines that I want from each chunk of data to be saved into the new file. I was also wondering if this method of reading and writing the data can be done by saving the data in a .mat file, because I have read that .mat files provide an efficient way of reading the data. I will be grateful to get any help regarding this.
Best wishes
AA

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采纳的回答

Walter Roberson
Walter Roberson 2012-6-12
Use 'a' instead of 'w'
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Geoff
Geoff 2012-6-12
Or you could use 'w' and just keep the file open until you're finished with it.

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更多回答（1 个）

Azza
Azza 2012-6-19
Many thanks Walter and Geoff...I think 'a' instead of 'w' is working perfectly with me.
Cheers
Azza

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