I tried it with replacing 'M' with 'M' and it worked. No need to worry about exotic characters.

use 5.014;

say 'iiiiiiiiMMMMMMMMMMMooooooooooooMMMMMMMMMMiiiiiMMMMMMMMoooo' 
      =~ tr/M/M/sr=~tr/M//;   # => prints: 3
[download]

No need for a new perl and the /r option either. This works fine:

#! perl -slw
use strict;
use Time::HiRes qw[ time ];

my $start = time;
my $count=0;
while( <DATA> ) {
#    $count += ()= m{M+}g;
    tr/M/M/s;
    $count += tr/M/M/;
}
print $count."\n";

printf "Took %9f secs\n", time() - $start;
[download]

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

But who knows, try to benchmark... :)

tr is MUCH faster than s though. I tried to work this out but didn’t hit on trizen’s cleverness. So…

# (v5.18.2) built for darwin-2level
    'tr' => sub {
        $str =~ tr/M/~/sr=~tr/~//;
    },
-- 
count      3
regex      3
regex2     3
split      3
tr         3

            Rate regex2  split  regex  count     tr
regex2  169354/s     --   -62%   -65%   -75%   -94%
split   446500/s   164%     --    -7%   -34%   -85%
regex   481882/s   185%     8%     --   -29%   -84%
count   674634/s   298%    51%    40%     --   -78%
tr     3044813/s  1698%   582%   532%   351%     --
[download]

Update: as trizen noted in his code, the /r flag to tr came in at 5.14. It won’t work on older Perls (update: <- stupid apostrophe begone).

> I tried to work this out but didn’t hit on trizen’s cleverness.

me too / neither =)

(tried /s but the returned count wasn't for groups)

> the /r flag to tr came in at 5.14. It won’t work on older Perls

If it's that fast using $str twice shouldn't be a big problem.

Should be mentioned that tr is destructive, i.e. a safety copy of the string may be needed too.

Cheers Rolf

_{(addicted to the Perl Programming Language and ☆☆☆☆ :)}