ReflectionParameter::getDefaultValueConstantName Returns the default value's constant name if default value is constant or null &reftitle.description; public stringReflectionParameter::getDefaultValueConstantName Returns the default value's constant name of the parameter of a user-defined function or method, if default value is constant or null. If the parameter is not optional a ReflectionException will be thrown. &reftitle.parameters; &no.function.parameters; &reftitle.returnvalues; Returns string on success or &null; on failure. &reftitle.examples; Getting default values' constant names of function parameters getParameters() as $param) { echo 'Name: ' . $param->getName() . PHP_EOL; if ($param->isOptional()) { echo 'Default value: ' . $param->getDefaultValueConstantName() . PHP_EOL; } echo PHP_EOL; } ?> ]]> &example.outputs; &reftitle.notes; Due to implementation details, it is not possible to get the default value of built-in functions or methods of built-in classes. Trying to do this will result a ReflectionException being thrown. &reftitle.seealso; ReflectionParameter::isOptional ReflectionParameter::isDefaultValueConstant ReflectionParameter::getDefaultValue