20:29: beretboy: s/ttt/tt/g;
20:34: alienhuman: /o would make that more efficient :)

##</code><code>##

$\="\n";
$_='aaa';
my $c='a';
print "$c:$_";
print "------";
print "$c:$_" while s/$c/$c++/oe; 
print "------";
print "$c:$_";

##</code><code>##

a:aaa
------
a:aaa
b:baa
c:bca
d:bcd
------
e:bcd

##</code><code>##

a:aaa
------
b:aaa
------
b:aaa

##</code><code>##

a:aaa
------
b:baa
c:caa
d:daa
e:eaa
f:faa
.....

##</code><code>##

21:45: alienhuman: /o would make that more efficient :)