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<ReflectionParameter::getDefaultValueReflectionParameter::getName>
^ReflectionParameterLast updated: Mon, 26 Oct 2026

ReflectionParameter::getDefaultValueConstantName

(PHP 5 >= 5.4.6, PHP 7, PHP 8)

ReflectionParameter::getDefaultValueConstantName — Returns the default value's constant name if default value is constant or null

Description

public function ReflectionParameter::getDefaultValueConstantName(): ?string

Returns the default value's constant name of the parameter of any user-defined or internal function or method, if default value is constant or null. If the parameter is not optional a ReflectionException will be thrown.

Parameters

This function has no parameters.

Return Values

Returns string on success or null on failure.

Changelog

Version Description
8.0.0 This method now allows getting the default values' constant names of built-in functions and built-in class methods. Previously, a ReflectionException was thrown.

Examples

Example #1 Getting default values' constant names of function parameters

<?php
function foo($test, $bar = PHP_INT_MIN)
{
    echo $test . $bar;
}

$function = new ReflectionFunction('foo');

foreach ($function->getParameters() as $param) {
    echo 'Name: ' . $param->getName() . PHP_EOL;
    if ($param->isOptional()) {
        echo 'Default value: ' . $param->getDefaultValueConstantName() . PHP_EOL;
    }
    echo PHP_EOL;
}
?>

The above example will output:

Name: test

Name: bar
Default value: PHP_INT_MIN

See Also


<ReflectionParameter::getDefaultValueReflectionParameter::getName>
^ReflectionParameterLast updated: Mon, 26 Oct 2026