Re: How do i find $a and replace it with $b when it's preceded by $c?

[nuance]

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;

produces moobaryou in $d