Re: [MLUG] String manipulation in C

[Mike Miller <EMAIL:PROTECTED>]

On Sun, 1 Jul 2007, Jack Smith wrote:

> So what I'd like to do is hack everything off of the first string after 
> the end of the first match. If I am looking for "ABC" in the following 
> string:
>
>     XXXXXABCXXXXXABCXX
>
> I'd like to reduce the string to
>
>    XXXXXABCXX


If I'm understanding your goal, this seems to be the perl way to do it:

s/^(.*?)ABC.*ABC(.*?)$/$1ABC$2/

If you have a bunch of files, you can do them all at once like so:

perl -pi -e 's/^(.*?)ABC.*ABC(.*?)$/$1ABC$2/' file*.txt

(where "ls file*.txt" would list all the files you wish to change and no 
others).

One thing that wasn't clear from your description is how to handle 
multiple matches to ABC -- the perl above deletes everything from the 
first match to the last match.  If there is one match in the line, it does 
nothing.

The question marks are supposed to turn off greediness of the matching 
algorithm.  The first question mark only helps if "ABC" occurs 3 or more 
times on the line.  The second question mark might not do anything, but I 
put it in there to be safe -- to be sure that .* is greedy and .*? is not 
greedy when there are multiple ABCs on the line.  But maybe the first .* 
would be greedy anyway so this will do the same thing:

perl -pi -e 's/^(.*?)ABC.*ABC(.*)$/$1ABC$2/' file*.txt

I feel more confident with the question mark in there that it is doing 
what I want.

Mike

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