- preg_match: documentation ( source)
<?php
$contents = "Start Test, the data follows.<br><br>\n\0";
echo "\n<br><br>The data is about to be passed to preg_match(). If you do not see the word 'Success' after this line, the program has crashed.<br>\n";
$truefalsetest=preg_match('%^(?:
[\x09\x0A\x0D\x20-\x7E] # ASCII
| [\xC2-\xDF][\x80-\xBF] # non-overlong 2-byte
| \xE0[\xA0-\xBF][\x80-\xBF] # excluding overlongs
| [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2} # straight 3-byte
| \xED[\x80-\x9F][\x80-\xBF] # excluding surrogates
| \xF0[\x90-\xBF][\x80-\xBF]{2} # planes 1-3
| [\xF1-\xF3][\x80-\xBF]{3} # planes 4-15
| \xF4[\x80-\x8F][\x80-\xBF]{2} # plane 16
)*$%xs', $contents);
echo "Success. Return value of preg_match() = $truefalsetest.";
?>