reading a writing to a text file

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

Answer 1

[Walter Roberson]

Use 'a' instead of 'w'

[Geoff]

Or you could use 'w' and just keep the file open until you're finished with it.

Answer 2

[Azza]

Many thanks Walter and Geoff...I think 'a' instead of 'w' is working perfectly with me.

Cheers

Azza