Extra content at the end of the document PHP and XML

Question

I having a strange problem when I\'m trying to produce an XML file with PHP. The problems is that, a strange question mark appears at the end of the source code. And I get t

Answer 1

I don't really have answer, accept that my editor wasn't showing the question mark. But one I opened the file in notepad2, lo and behold, the question mark was there. Very strange. Thanks for your help.