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Re: Fast editing of text file? [message #44469 is a reply to message #44448]

Thu, 16 June 2005 07:51

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

t_314159@yahoo.com writes:
> Hi,
> I have a text file that I must access many times during program
> execution (1000's of times, really!) and I *always* only need to change
> the the text on the 12th line of the file. My question, how to
> efficiently access and alter the text of ONLY the 12th line without
> altering even a single space or comma on any of the rest of the lines?
> And did I mention fast since i've got to loop through this many times?

If you can keep each line a fixed record size, then it might be
easiest to write lines 1-11, use POINT_LUN to determine the file
pointer position, and then write the rest of the file.

After that, you can open the file in update mode, (OPENU), and
POINT_LUN directly to the position of line 12, rewrite it, and
proceed. However, this procedure only works if line 12 has a fixed
record size.

Good luck,
Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: Fast editing of text file? By: R.Bauer on Sun, 19 June 2005 01:12
		Re: Fast editing of text file? By: Craig Markwardt on Thu, 16 June 2005 07:51
		Re: Fast editing of text file? By: Michael Wallace on Thu, 16 June 2005 01:05
		Re: Fast editing of text file? By: Mark Hadfield on Wed, 15 June 2005 20:28
		Re: Fast editing of text file? By: Andrew Cool on Wed, 15 June 2005 19:55
		Re: Fast editing of text file? By: marc schellens[1] on Wed, 15 June 2005 00:55
		Re: Fast editing of text file? By: Michael Wallace on Tue, 14 June 2005 21:22
		Re: Fast editing of text file? By: t_314159 on Tue, 14 June 2005 17:15
		Re: Fast editing of text file? By: Michael Wallace on Tue, 14 June 2005 16:26

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