Description
bool 
is_dir ( string filename )
     Returns TRUE if the filename exists and is a directory. If
     filename is a relative filename, it will be
     checked relative to the current working directory.
    
Note: The results of this 
function are cached. See clearstatcache() for 
more details.
     
Example 1. is_dir() example 
<? var_dump(is_dir('a_file.txt')) . "\n"; var_dump(is_dir('bogus_dir/abc')) . "\n";
  var_dump(is_dir('..')); //one dir up ?>
 |  
 The above example will output: bool(false)
bool(false)
bool(true)  |  
  | 
    Tip: As of PHP 5.0.0 this function
can also be used with some URL wrappers.  Refer to 
Appendix M for a listing of which wrappers support 
stat() family of functionality.
     See also chdir(), dir,
     opendir(), is_file() and
     is_link().