// Define a dummy text, for testing...
$Text = \"Title: Hello world!\\n\";
$Text .= \"Author: Jonas\\n\";
$Text .= \"This is a example message!\\n\\n\";
$Text .= \"Title: Entry 2\\n\";
$Text .= \"Author: Sonja\\n\";
$Text .= \"Hello world, what\'s up!\\n\";
// This function will replace specific matches
// into a new form
function RewriteText($Match){
  // Entire matched section: 
  // --> /.../
  $EntireSection = $Match[0];
  // --> \"\\nTitle: Hello world!\"
  // Key 
  // --> ([a-z0-9]+)
  $Key      = $Match[1];
  // --> \"Title\"
  // Value 
  // --> ([^\\n\\r]+)
  $Value    = $Match[2];
  // --> \"Hello world!\"
  // Add some bold (<b>) tags to around the key to
  return \'<b>\' . $Key . \'</b>: \' . $Value;
}
// The regular expression will extract and pass all \"key: value\" pairs to
// the \"RewriteText\" function that is definied above
$NewText = preg_replace_callback(\'/[\\r\\n]([a-z0-9]+): ([^\\n\\r]+)/i\', \"RewriteText\", $Text);
// Print the new modified text
print $NewText;