Bit long winded. Why not
Code:
$file = date("d").'html';
include($file);
or
Code:
$file = date("d").'html';
$myFile = file($file);
echo $myFile;
Then, if your files are called 01.html, 02.html, 03.html .... 30.html, 31.html, then you will be setting the variable
$file to be whatever the day is eg
10.html