find and replace counter

texuser74 has asked for the wisdom of the Perl Monks concerning the following question:

hi monks, I need to insert a counter tag for all <xxx> tag.

Input:
<xxx>...</xxx>
<p>...</p>
<xxx>...</xxx><xxx>...</xxx>
<p>...</p>
[download]

Output:
<1><xxx>...</xxx>
<p>...</p>
<2><xxx>...</xxx><3><xxx>...</xxx>
<p>...</p>
[download]

my present code inserts only for first occurance of <xxx>.

   if(/<xxx>/){
    s/(<xxx>)/<$cnt>$1/;
    ++$cnt;
    }
[download]

pls, help me how to code this.

Comment on find and replace counter Select or Download Code

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Re: find and replace counter by msbalaji (Chaplain) on Jan 08, 2008 at 06:38 UTC
hi try this `use strict; my $cnt=0; while(<DATA>){ $_ =~s/<xxx>/++$cnt.$&/gie; print $_; } __DATA__ <xxx>...</xxx> <p>...</p> <xxx>...</xxx><xxx>...</xxx> <p>...</p>` [download] Regards Balaji. M	[reply] [d/l]
Re^2: find and replace counter by hipowls (Curate) on Jan 08, 2008 at 07:20 UTC
Global substitution along with 'e' to evaluate the replacement text is the trick although you'd be better off not using $& as it imposes a cost on all regular expessions in the program. See Special variables. And you left out the '<' and '>'. Given that `<xxx>` is a constant string it isn't worth while capturing it. If the tag is to be passed in a function then something like `my $html = get('http://use.perl.org'); my $tag = '<xxx>'; # or '<' . shift . '>' or ... my $count = 0; $html =~ s/$tag/ '<' . ++$count . ">$tag" /ge;` [download] The reference to LWP::Simple was inspired by this blog on Beautiful Code	[reply] [d/l] [select]
Re^2: find and replace counter by texuser74 (Monk) on Jan 08, 2008 at 07:11 UTC
Thanks Balaji, that solves my problem	[reply]
Re: find and replace counter by poolpi (Hermit) on Jan 08, 2008 at 09:24 UTC
Another way to do it ;) `#!/usr/bin/perl use strict; use warnings; local $/; local $_ = <DATA>; my $c; s/(<xxx>)(?{++$c;})/<$c>$1/g; print; __DATA__ <xxx>fo</xxx> <p>ba</p> <xxx>foo</xxx><xxx>bar</xxx> <p>foobar</p>` [download] Output: `<1><xxx>fo</xxx> <p>ba</p> <2><xxx>foo</xxx><3><xxx>bar</xxx> <p>foobar</p>` [download] HTH, PooLpi	[reply] [d/l] [select]