graste/regex_test.php

## regex_test.php
<?php

$pattern = <<<EOT
/
    (?(DEFINE)
        (?<T_NUM> [0-9] )
    )
    ^(?&T_NUM)$
/x
EOT;
$text = '1';

if (preg_match($pattern, $text))
{
        echo "matched!\n";
}
else
{
        echo "no match!\n";
}
	<?php

	$pattern = <<<EOT
	/
	(?(DEFINE)
	(?<T_NUM> [0-9] )
	)
	^(?&T_NUM)$
	/x
	EOT;
	$text = '1';

	if (preg_match($pattern, $text))
	{
	echo "matched!\n";
	}
	else
	{
	echo "no match!\n";
	}