If all you want to do is check the presence of M using tr/// then it is simple:

#!/usr/bin/env perl 
use strict;
use warnings;

my $s='IIIIIIIIIIIIIIIIIIIIIIIIIIOOOOOSSSSS';

print "$s: " . ($s =~ tr/M/M/ ? "case1\n" : "case2\n");

$s .= 'M';

print "$s: " . ($s =~ tr/M/M/ ? "case1\n" : "case2\n");

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In reply to Re^3: Pattern matching regex problem by hippo
in thread Pattern matching regex problem by Anonymous Monk

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