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how to replace line on particular line in file[no need to write it back whole file again]

On 2018-10-11 09:01:55 -0400, Dennis Lee Bieber wrote:
> On Thu, 11 Oct 2018 15:14:49 +0530, Iranna Mathapati
> <iranna.gani28 at gmail.com> declaimed the following:
> >How to replace particular line text with  new text on a file
> >i have below code but its writing whole code.
> >
> 	For C-style streams (which seem to have taken over every operating
> system) in which "lines" are determined by specific characters in the
> stream, you can only "replace" a line IF THE REPLACEMENT IS THE EXACT SAME
> SIZE! If there is any difference in length of the input and output lines,
> you have to read/write everything from the line to the end of the file.
> 	I emphasize "C-style streams" as there were operating systems that did
> support other file organizations natively.

And therefore you should call them "Unix-style streams".

> Xerox CP-V offered "consecutive", "keyed", and "random" file
> organizations. 

I don't know if there was a C implementation for CP-V, but there is
certainly nothing in the C standard which would prevent a standard
conforming implementation of those file organizations.


   _  | Peter J. Holzer    | we build much bigger, better disasters now
|_|_) |                    | because we have much more sophisticated
| |   | hjp at hjp.at         | management tools.
__/   | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
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