#!/usr/bin/env perl

use strict;
use warnings;

my $string = '2cat6';
my @chars = split //, $string;
my @tests = qw{2cat6 cat catch vwxyz 12345 67890 13457};

TEST: for my $test (@tests) {
    for my $char (@chars) {
        if (0 <= index $test, $char) {
            print "$test: true\n";
            next TEST;
        }
    }

    print "$test: false\n";
}

##</code><code>##

2cat6: true
cat: true
catch: true
vwxyz: false
12345: true
67890: true
13457: false