1--TEST-- 2ReflectionParameter::getDefaultValue() should also work for parameters of internal functions. 3--FILE-- 4<?php 5$class = new ReflectionClass('DateTime'); 6$method = $class->getMethod('setTime'); 7 8foreach ($method->getParameters() as $k => $parameter) { 9 try { 10 var_dump($parameter->getDefaultValue()); 11 } catch (ReflectionException $exception) { 12 echo $exception->getMessage() . "\n"; 13 } 14} 15 16echo "----------\n"; 17 18$class = new ReflectionClass('DateTimeZone'); 19$method = $class->getMethod('listIdentifiers'); 20 21foreach ($method->getParameters() as $parameter) { 22 try { 23 var_dump($parameter->getDefaultValue()); 24 } catch (ReflectionException $exception) { 25 echo $exception->getMessage() . "\n"; 26 } 27} 28 29?> 30--EXPECT-- 31Internal error: Failed to retrieve the default value 32Internal error: Failed to retrieve the default value 33int(0) 34int(0) 35---------- 36int(2047) 37NULL 38