Preg_match examples

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The preg_match examples source code

<html>
<body>
<?

echo '<h2>Preg match [code] example:</h2><br />';
$string='This is before the code brackets [code]We are inside the square brackets[/code] And again after';
/*Pay attention to the '\' character - The pattern we are looking for is matched by the (.+) which we could have changed to (.*) to also retrieve an empty string.*/
preg_match("/\[code\](.+)\[\/code\]/",$string, $results);
echo 'Results: '.$results[1];

echo '<h2>Preg Match '.htmlentities('<head>').' example:</h2>';

$string='<html><head something which is often inputed here><title>Title</title><meta name="description" content="description of your page" /></head><body>The body of your page<br />some text...</body></html>';

/*Note the use of '/smU' which is very useful for case insensitive matching and other features (report to the pattern modifiers manual)*/
preg_match("/<head.*>(.*)<\/head>/smU",$string, $results);
echo 'Results: '.htmlentities($results[1],ENT_QUOTES);

echo '<h2>Preg Match meta description example:</h2>';

/*Note the use of '^' which negate a pattern*/
preg_match("|<meta[^>]*description[^>]*content=\"([^>]+)\"[^>]*>|Ui",$string, $results);
echo 'Results: '.$results[1];

/*A very famous example here:*/
echo '<h2>Host from Url example:</h2>';
$url='http://www.linkstraffic.net/traffic.php';
preg_match('@^(?:http://)?([^/]+)@i',$url, $matches);
$host = $matches[1];
echo '<br />Host: '.$host.'<br />';
preg_match('/[^.]+\.[^.]+$/', $host, $matches);
echo "domain name is: {$matches[0]}<br />";

/*The Charset example*/
$string='<meta http-equiv="content-type" content="text/html; charset=gb2312">';
echo '<h2>Charset Example</h2>';
preg_match("/<meta[^>]*http-equiv[^>]*charset=(.*)(\"|')>/Ui",$string, $results);
echo 'Results: '.$results[1];

/*The input value example (we have the name)*/
$string='<input type="text" name="thename" value="somevalue" />';
echo '<h2>Input value example</h2>';
preg_match("/<input[^>]*name=\"thename\"[^>]*value=[\"|'](.*)[\"|']/Ui",$string, $results);
echo 'Results: '.$results[1];

/*preg_match_all example with text contained inside [url] tags to extract*/
$string='some text before [url]http://www.newo17.com[/url] and another url here: [url]http://www.remotehireman.com[/url]. Check out the links if you have time ;).';
echo '<h2>preg_match_all example</h2>';
echo '<p><u>Text to parse</u>:<br /> '.$string.'</p>';
preg_match_all("|\[url\](.*)\[\/url\]|U",$string,$results,PREG_SET_ORDER);
foreach ($results as $val) 
{
	$string=str_replace($val[0],'<a href="'.$val[1].'" target="_blank">...'.substr($val[1],-20).'</a>',$string);
}

echo '<u>Extracted text</u>:<br />'.$string.'</p>';

?>
</body>
</html>

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When working with this function, you should have a close look to these pages:
- manual/en/function.preg-match
- manual/en/reference.pcre.pattern.syntax
- reference.pcre.pattern.modifiers

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Preg_match examples

Preg_match examples

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