[wp-hackers] Constant for Theme File Path

[Austin Matzko]

On Fri, Jan 7, 2011 at 1:17 PM, Chip Bennett <chip at chipbennett.net> wrote:
> I need to check for the existence of the default Theme (i.e. TwentyTen),
> which is easy enough: use file_exists() to find twentyten/style.css.
>
> WordPress has a defined constant, WP_PLUGIN_DIR, for retrieving the file
> path (not URL) of the directory in which Plugins are installed. Does a
> similar constant (or other means) exist for retrieving the file path (not
> URL) of the directory in which Themes are installed?

How about get_theme_root() ?