get_defined_constants Returns an associative array with the names of all the constants and their values arrayget_defined_constants This function returns the names and values of all the constants currently defined. This includes those created by extensions as well as those created with the define function. For example the line below: ]]> will print a list like: 1 [E_WARNING] => 2 [E_PARSE] => 4 [E_NOTICE] => 8 [E_CORE_ERROR] => 16 [E_CORE_WARNING] => 32 [E_COMPILE_ERROR] => 64 [E_COMPILE_WARNING] => 128 [E_USER_ERROR] => 256 [E_USER_WARNING] => 512 [E_USER_NOTICE] => 1024 [E_ALL] => 2047 [TRUE] => 1 ) ]]> See also get_loaded_extensions, get_defined_functions, and get_defined_vars.