PHP Manual . ... To declare functions that are to be exported (i.e., made available to PHP as new native functions), Zend provides a set of macros. ... ZEND_FUNCTION declares a new C function that complies with Zend's internal API. ... void zif_my_function(int ht, zval *return_value, zval *this_ptr, int return_value_used, zend_executor_globals *executor_globals); . ... Zend's Parameters to Functions Called from PHP . ... This variable is used to pass any return values of your function back to PHP. ...