Example 11-3. pc_ascii2html( )

function pc_ascii2html($s) {
  $s = htmlentities($s);
  $grafs = split("\n\n",$s);
  for ($i = 0, $j = count($grafs); $i < $j; $i++) {
    // Link to what seem to be http or ftp URLs
    $grafs[$i] = preg_replace('/((ht|f)tp:\/\/[^\s&]+)/',
                              '<a href="$1">$1</a>',$grafs[$i]);

    // Link to email addresses
    $grafs[$i] = preg_replace('/[^@\s]+@([-a-z0-9]+\.)+[a-z]{2,}/i',
        '<a href="mailto:$1">$1</a>',$grafs[$i]);

    // Begin with a new paragraph 
    $grafs[$i] = '<p>'.$grafs[$i].'</p>';
  }
  return join("\n\n",$grafs);
}