# ReflectionProperty::getDefaultValue

(PHP 8)

ReflectionProperty::getDefaultValue — Returns the default value declared for a property

### 说明

public ReflectionProperty::getDefaultValue(): mixed

Gets the implicit or explicitly declared default value for a property.

### 参数

此函数没有参数。

### 返回值

The default value if the property has any default value (including `null`). If there is no default value, then `null` is returned. It is not possible to differentiate between a `null` default value and an unitialized typed property. Use ReflectionProperty::hasDefaultValue() to detect the difference.

### 示例

示例 #1 ReflectionProperty::getDefaultValue() example

`<?php
class Foo {
public $bar = 1;
public ?int $baz;
public int $boing = 0;
public function __construct(public string $bak = "default") { }
}
$ro = new ReflectionClass(Foo::class);
var_dump($ro->getProperty('bar')->getDefaultValue());
var_dump($ro->getProperty('baz')->getDefaultValue());
var_dump($ro->getProperty('boing')->getDefaultValue());
var_dump($ro->getProperty('bak')->getDefaultValue());
?>`

以上示例会输出：

    int(1)
    NULL
    int(0)
    NULL

### 参见

- ReflectionProperty::hasDefaultValue() - Checks if property has a default value declared

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