use strict;
sub commify {
    reverse scalar join ',',
    unpack '(A3)*',
    reverse scalar shift;
}
sub commify2 {
    scalar reverse join ',',
    unpack '(A3)*',
    reverse scalar shift;
}
my $x = commify(1234);
my $y = commify2(1234);
print "x='$x' y='$y'\n";
print "comm :", commify(1234), ":\n";
print "comm2:", commify2(1234), ":\n";