Re: fopen: pre-pending text

joe.user0@xxxxxxxxx wrote:
>Coding in C, I can append text to a file
>e.g. as with
>
> fopen ("txtfile", a+)
>
>To write at the begin of file, I can use
>
> fopen ("txtfile", r+)
>
>but that will overwrite existing text.
>
>So how do I insert (pre-prend) text with fopen?

1) open original file for reading
2) open a temp file for writing
3) write new text to temp file
4) write original file to end of temp file
5) close both files
6) verify temp file (using stat or whatever) has desired data
7) open temp file for reading
8) open original file for writing at start of file
9) write temp file to original file
10) close both files
11) verify original file now has new data
12) unlink temp file

Of course if the data is not particularly sensitive, and losing
it would not be the end of the world, several steps there can be
eliminated.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@xxxxxxxxxx
.

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