php-网页正常运行，但是网页最下端多出来两行代码，为什么？

Warning: include(footer.php) [function.include]: failed to open stream: No such file or directory in D:\phpStudy\WWW\index.php on line 19

Warning: include() [function.include]: Failed opening 'footer.php' for inclusion (include_path='.;C:\php\pear') in D:\phpStudy\WWW\index.php on line 19