Perl/Regex question (hopefully simple)

[Madison Kelly]

G. Matthew Rice wrote:
> Madison Kelly <linux-5ZoueyuiTZhBDgjK7y7TUQ at public.gmane.org> writes:
> 
>>$help_body =~ s/\[url=(.*)\](.*)\[\/url\]/<a href="\1"
>>target="_new">\2<\/a>/gi;
>>
>>Which seems very much like what you both recommended. Do you know if one
>>method is better or worse than the other or are they just two ways to do the
>>same thing?
> 
> 
> Read the perlre manpage.  Scan for the section 'Warning on \1 vs $1'.  Plus
> you get the $1, $2, ... after a m// operation is over.
> 
> Aww, what the heck.  Here it is:
> 
>        Warning on \1 vs $1
> 
>        Some people get too used to writing things like:
> 
>            $pattern =~ s/(\W)/\\\1/g;
> 
>        This is grandfathered for the RHS of a substitute to avoid
>        shocking the sed addicts, but it's a dirty habit to get
>        into.  That's because in PerlThink, the righthand side of
>        a "s///" is a double-quoted string.  "\1" in the usual
>        double-quoted string means a control-A.  The customary
>        Unix meaning of "\1" is kludged in for "s///".  However,
>        if you get into the habit of doing that, you get yourself
>        into trouble if you then add an "/e" modifier.
> 
>            s/(\d+)/ \1 + 1 /eg;        # causes warning under -w
> 
>        Or if you try to do
> 
>            s/(\d+)/\1000/;
> 
>        You can't disambiguate that by saying "\{1}000", whereas
>        you can fix it with "${1}000".  The operation of interpo-
>        lation should not be confused with the operation of match-
>        ing a backreference.  Certainly they mean two different
>        things on the left side of the "s///".
> 
> HTH,

Thanks! That clears some stuff up and I've changed them to $<#>.

Madison
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