in reply to How do i find $a and replace it with $b when it's preceded by $c?

A postivive look behind clause in the regular expression will do what you want. 
my($a, $b, $c, $d) = qw{foo bar moo moofooyou);

$d =~ s/(?<=$c)$a/$b/g;

[download]
produces moobaryou in $d
  • Comment on Re: How do i find $a and replace it with $b when it's preceded by $c?
  • Download Code

In Section Seekers of Perl Wisdom