#! perl -slw
use strict;

my @examples = qw[ AB23C ABC23 23BC ABC ];

m[([A-Z]*)([0-9]*)([A-Z]*)]
    and printf "%s: '%s', '%s', '%s'\n", $_, $1//'', $2//'', $3//''
    for @examples;

__END__
C:\test>1148522
AB23C: 'AB', '23', 'C'
ABC23: 'ABC', '23', ''
23BC: '', '23', 'BC'
ABC: 'ABC', '', ''