Regular expression replace a word by a link

Question

I want to write a regular expression that will replace the word Paris by a link, for only the word is not ready a part of a link.

Example:

    i\'m l         


        

Answer 1

  $pattern = 'Paris';
  $text = 'i\'m living in Paris,  near Paris Gare du Nord,  i love Paris.';

  // 1. Define 2 arrays:
  //  $matches[1] - array of links with our keyword
  //  $matches[2] - array of keyword
  preg_match_all('@(]*?>[^<]*?'.$pattern.'[^<]*?)|(?
  $number = array_search($pattern, $matches[2]);

  // Keyword exists, let's go rock
  if ($number !== FALSE) {

    // Replace all link with temporary value
    foreach ($matches[1] as $k => $tag) {
      $text = preg_replace('@(]*?>[^<]*?'.$pattern.'[^<]*?)@', 'KEYWORD_IS_ALREADY_LINK_'.$k, $text, 1);
    }

    // Replace our keywords with link
    $text = preg_replace('/(?'.$pattern.'', $text);

    // Return link
    foreach ($matches[1] as $k => $tag) {

      $text = str_replace('KEYWORD_IS_ALREADY_LINK_'.$k, $tag, $text);
    }

    // It's work!
    echo $text;
  }