pat_mc:

You might try using a zero-width positive lookahead assertion. I've not used them much, so there may be some gotchas in their general use. But for a simple usage like yours, it's not so bad:

$ cat u.pl
use strict;
use warnings;

while ('aaa' =~/a(?=a)/g) {
    print $-[-1], "\n"
}

$ perl u.pl
0
1
[download]

Read about them in perldoc perlre in the "Look-Around Assertions" section.

...roboticus

When your only tool is a hammer, all problems look like your thumb.