#!/usr/bin/perl
use strict;
use warnings;
use POSIX;

sub intlength ($);

print "$_: ", intlength($_) , "\n" for (-1_001..-998,-101..101,998..1_001,123_456_789);

sub intlength ($) {
    my $zahl  = shift;
    my $minus = $zahl<0?1:0;

    return 1 if $zahl == 0;
    return 2 if $zahl == -1;

    $zahl = -$zahl if $minus;

    return POSIX::ceil(log($zahl+1)/log(10)) + $minus;
}