Dynamically Generate Link From Text

<?php
   $txt = "http://www.google.com/test";
   $txt = preg_replace( "/(?<!<a href=\")((http|ftp)+(s)?:\/\/[^<>\s]+)/i", "<a href=\"\\0\">\\0</a>", $txt );
   echo $txt;
?>

Assuming that $content is the content you wish to parse through, this will turn the new lines into <BR />, make email links into proper mailto links, and add http:// should the user have forgotten to do that.  


      $content = nl2br($content);
      $str = $content;
       $str = eregi_replace ("[[:alpha:]]+://www", "www",$str);
       $str = ereg_replace ("[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/](\.[a-z0-9-]{2,4})+", "<a href=\\0 target=_blank>\\0</a>", $str);
       $str = ereg_replace ("www.[^<>[:space:]]+[[:alnum:]/](\.[a-z0-9-]{2,4})+", "<a href=http://\\0 target=_blank>\\0</a>", $str);
       $str = ereg_replace ("[[:alpha:]]+@[^<>[:space:]]+[[:alnum:]/](\.[a-z0-9-]{2,4})+", "<a href=mailto:\\0 target=_blank>\\0</a>", $str);
      $content = $str;