You might try something like this:

#!/perl/bin/perl -w
use strict;

my $str        = 'ffggffffhhffii';
my $searchstr1 = 'ff';
my $searchstr2 = 'ee';

my @ary1       = $str =~ /$searchstr1/g;
my @ary2       = $str =~ /$searchstr2/g;

printf qq("%s" matches "%s" %d times.\n), $searchstr1, $str, scalar @a
+ry1;
printf qq("%s" matches "%s" %d times.\n), $searchstr2, $str, scalar @a
+ry2;

__OUTPUT__
"ff" matches "ffggffffhhffii" 4 times.
"ee" matches "ffggffffhhffii" 0 times.
[download]

Update: Ugh! First solution was borked... this version works better...

Update2: Removed unnecessary parentheses from regex