with error handling

gistfile1.php

#!/usr/bin/env php
<?php

if(!isset($argv[1])) {
    echo 'Usage: ' . $argv[0] . ' <dddd>';
} else if(4 !== strlen($argv[1])) {
    trigger_error('Input must be only 4 digits');
} else if(false !== strpos($argv[1],'4')) {
    trigger_error('No body likes 4s anyway');
} else {
    $map = array(
        '0'=>1,
        '1'=>0,
        '2'=>0,
        '3'=>0,
        // 4 is not accounted for
        '5'=>0,
        '6'=>1,
        '7'=>0,
        '8'=>2,
        '9'=>1
    );

    $result = 0;

    foreach(str_split($argv[1],1) as $digit) {
        if(array_key_exists($digit, $map)) {
            $result += $map[$digit];
        }
    }

    echo $result . "\n";
}