- var_dump: documentation ( source)
- filter_var: documentation ( source)
<?php
$val1 = "42 Day";
$val2 = "3 week;stuff";
$opts = ['regexp' => "/^[0-9]+ (month|day|hour)$/i"];
$f1 = filter_var($val1, FILTER_VALIDATE_REGEXP, ['options' => $opts]);
$f2 = filter_var($val2, FILTER_VALIDATE_REGEXP, ['options' => $opts]);
var_dump($f1);
var_dump($f2);