$str = '11,你好|12,他好|13,我好|14,都好|15,大家好';
$arr = array();
if (!empty($str)) {
    preg_match_all('/(\d{2})/', $str, $match);
    $i = 0;
    foreach ($match[1] as $value) {
        ++$i;
        $arr['tag' . $i] = $value;
    }
} else {
    for ($i = 1; $i < 6; $i++) {
        $arr['tag' . $i] = 0;
    }
}