问如何在perl中检查一个数字是否以其他数字开头

EN

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

sub prefix_in_list {
    my ($needle, $haystack) = @_;
    my $regex = join '|', @$haystack;
    return $needle =~ /^(?:$regex)/
}

use Test::More tests => 3;

ok prefix_in_list(45789277, [1, 2, 45, 757, 3, 7466]);

ok ! prefix_in_list(55366363, [1, 4, 3]);

ok prefix_in_list(55366363, [6535, 55, 1, 8]);

sub compute_length {
    my ($n) = @_;
    return int(log($n) / log 10)
}

sub prefix_in_list {
    my ($needle, $haystack) = @_;
    for my $prefix (@$haystack) {
        my $start = $needle;
        my $divider = 10 ** (compute_length($start) - compute_length($prefix));
        return 1 if int($start / $divider) == $prefix;
    }
    return
}

# Checks if a number $num has a prefix given by an item in @$list
sub starts_width {
    my ( $num, $list ) = @_;

    for (@$list) {
        return 1 if (substr $num, 0, length $_) eq $_;
    }
    return 0;
}

return 1 if (index $num, $_) == 0;