I’m not too experienced in PHP myself, but unlike ASP you won’t necessarily need the absolute path to a file with php with write operations.
e.g. I use this snippet to write to a file using a relative path from the script to the file in question. (Note the forward slashes, too.) Or you can use a preceding ‘/’ to make it relative to the root folder of the website.
$filename=“folder/another_folder/my_file.txt”;
$file = fopen($filename,“w”) or die(“Can’t open file”);
etc.
that relative path should work best, but if you need absolute try the d:\hshome\user\domain.com format many times you need \ on PHP for the slashes, just as a note.