PHP preg_match and regular expression

Question

I'm new for PHP

I am trying to get topic number of link but not work.

echo $topicsave is empty.

This my code.

$data = '
<a href="http://forums.inwing.com/index.php/topic,40500.0.html">test_curl</a>
';
preg_match_all('/\<a[^\?]+\/([^\"]+)\.\s*\>test_curl\<\/a\>/', $data, $match);
    echo '<pre>',htmlspecialchars(print_r($match, true)),'</pre>';
    if( count($match[0])){
    foreach($match[1] as $vl){
        preg_match_all('/topic\,([0-9]+\.[0-9]+)/', $vl, $m1);
        if(count($m1[1])) 

           $topicsave = $m1[1][0];
           echo $topicsave;

    }
}

I want to get topic number 40500 please help me, topic is variable such as 120 or 2536 or 12456 .

Thank you.

Answer 1

To extract the topic number from link you can use following regex.

Regex: topic,(\\d+(\\.\\d+)*)\\.html

Explanation: What am doing is feeding your link to regex and extracting number between topic, and .html .

Regex101 Demo

PHP demo on Ideone

Answer 2

You can do it with this:

$re = "/topic,(?'topic'\\d+)/"; 
$str = "<a href=\"http://forums.inwing.com/index.php/topic,40500.0.html\">test_curl</a>"; 

preg_match($re, $str, $matches);

echo $matches['topic'];

Which will output:

40500

What I used here (?'topic'\\\\d+) is a named group . It allows you to retrieve data from your matches with the name you used (here topic ).

If you need to do live tests, Regex 101 is great.

Answer 3

Try this solution:

$data = '<a href="http://forums.inwing.com/index.php/topic,40500.0.html">test_curl</a>';
preg_match_all('/topic,(.*?)\..*\.html/s', $data, $match);    
echo $match[1][0]; // Output: 40500