My goal was more complex than what’s described here in, but I wanted to share a simple function for returning the links in some HTML (now that I know what I’m doing)… Hopefully someone finds this useful, it was a common question in forums I noticed.

Regular expressions are a power tool for working with strings. PHP provides support for a couple of different types but I’m using preg (aka the Perl compatible one).

The regular expression I put together for this was:

/<a\s[^>]*href=”(?P<href>[^"]*)”\s[^>]*>(?P<name>.*)<\/a>/si

What this means is:

• / - perl regular expression patterns are enclosed in forward slashes (this is the opening one)
• <a - is satisfied literally (the open of the html a tag)
• \s - is a single whitespace character (includes line breaks etc)
• [^>]* - satisfied by any characters except >, this can be satisfied zero - many times (allows for anything else inside the html a tag)
  • [ ] - a charter class
  • ^ - except the following
  • > - is satisfied literally
  • * - the charter class can occur zero of many times
• href=” - is satisfied literally
• (?P<href>[^"]*) - match and return as ‘href’ - any characters except “, this can be satisfied zero - many times (gets everything inside the href attribute)
  • ( ) - match and return
  • ?P<href> - nominate the name we’ll return it as ‘href’ could be anything you like!
  • [^"]* - satisfied by any characters except “, this can be satisfied zero - many times
• > - is satisfied literally (the close of the html a tag)
• (?P<name>.*) - match and return as name - any character, this can be satisfied zero - many times (gets everything inside the a tag)
  • ( ) - match and return
  • ?P<name> - nominate the name we’ll return it as ‘name’.
  • .* - satisfied by any character, this can be satisfied zero - many times
• <\/a> - is satisfied literally (but we’re escaping the forward slash we don’t want to end up pattern here)
• / - now we want to end our pattern!
• si - the trailing s and i are modifiers to change the way the expression is interpreted
  • s - means the . we’ve used can also represent line breaks (normally it doesn’t)
  • i - means the entire thing is case insensitive!

A PHP function using this might look like so:

private function getLinks($responseBody){
    $_regexp = '/<a\s[^>]*href="(?P<href>[^"]*)"\s[^>]*>(?P<name>.*)<\/a>/si';
    preg_match_all($_regexp, $responseBody, $matches);
 
    $i = 0;
    foreach($matches['name'] as $name) {
        $links[$i]['name'] = trim($name);
        $i++;
    }
 
    $i = 0;
    foreach($matches['href'] as $href) {
        $links[$i]['href'] = $href;
        $i++;
    }
 
    return $links;
}

Issues with this regular expression I know I haven’t address are:

• You’re link may not be text, it could be an image or anything!
• Not everyone using double quotes for their attributes.
• Browsers support sloppy HTML this experession doesn’t! E.g. <a href = /link/>

Any corrections or feedback would be pleased to hear from you!