1. Constant
    1. define('ROOTURI', get_template_directory_uri() );
    2. Automatically global.
  2. basename()
    1. File or last folder name of a path
    2. echo basename(ROOTURI);
      1. myTheme.
  3. dirname()
    1. Directory name of a path.
  4. include ()
    1. $mobile_path =plugin.php';
      if ( file_exists( $mobile_path ) ) { include( $mobile_path ); }
    2. if ( file_exists( ROOTDIR . '/a/setup.php' ) ) include( ROOTDIR . '/a/setup.php' );
  5. stripos(string,find,start)
    1. Position number of the first occurrence inside the string: