#! perl -w
use strict;

my $str = 'a' x 100000;
my $char = 'a';

for my $n ( map{ $_ * 1000 + 165 } 1 .. 30 ) {
    pos($str)=0;
    $str =~ /(?:.*?$char){$n}/g;
    print "Pos of '$char' #$n in \$str is ", pos($str), "\n";
}

__END__
C:\test>junk
Pos of 'a' #1165 in $str is 1165
Pos of 'a' #2165 in $str is 2165
Pos of 'a' #3165 in $str is 3165
Pos of 'a' #4165 in $str is 4165
Pos of 'a' #5165 in $str is 5165
Pos of 'a' #6165 in $str is 6165
Pos of 'a' #7165 in $str is 7165
Pos of 'a' #8165 in $str is 8165
Pos of 'a' #9165 in $str is 9165
Pos of 'a' #10165 in $str is 10165
Pos of 'a' #11165 in $str is 11165
Pos of 'a' #12165 in $str is 12165
Pos of 'a' #13165 in $str is 13165
Pos of 'a' #14165 in $str is 14165
Pos of 'a' #15165 in $str is 15165
Pos of 'a' #16165 in $str is 16165
Pos of 'a' #17165 in $str is 17165
Pos of 'a' #18165 in $str is 18165
Pos of 'a' #19165 in $str is 19165
Pos of 'a' #20165 in $str is 20165
Pos of 'a' #21165 in $str is 21165