How to automatically add links to URLs

This article example shows how php automatically adds links to URLs. Share it for your reference. The specific implementation method is as follows:

Here we automatically match the URL in the page, including http, ftp, etc., and automatically add links to the URL

function text2links($str='') {
  if($str=='' or !preg_match('/(http|www\.|@)/i', $str)) { return $str; }
  $lines = explode("\n", $str); $new_text = '';
  while (list($k,$l) = each($lines)) {
    // replace links:
    $l = preg_replace("/([ \t]|^)www\./i", "\\1http://www.", $l);
    $l = preg_replace("/([ \t]|^)ftp\./i", "\\1ftp://ftp.", $l);
    $l = preg_replace("/(http:\/\/[^ )\r\n!]+)/i",
      "&lt;a href=\"\\1\"&gt;\\1&lt;/a&gt;", $l);
    $l = preg_replace("/(https:\/\/[^ )\r\n!]+)/i",
      "&lt;a href=\"\\1\"&gt;\\1&lt;/a&gt;", $l);
    $l = preg_replace("/(ftp:\/\/[^ )\r\n!]+)/i",
      "&lt;a href=\"\\1\"&gt;\\1&lt;/a&gt;", $l);
    $l = preg_replace(
      "/([-a-z0-9_]+(\.[_a-z0-9-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)+))/i",
      "&lt;a href=\"mailto:\\1\"&gt;\\1&lt;/a&gt;", $l);
    $new_text .= $l."\n";
  }
  return $new_text;
}
 
//Usage example:$text = "Welcome  :-)";
print text2links($text);

I hope this article will be helpful to everyone's PHP programming.