(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)
get_defined_constants — 返回所有常量的关联数组，键是常量名，值是常量值
$categorize = false
) : array返回当前所有已定义的常量名和值。 这包含 define() 函数所创建的，也包含了所有扩展所创建的。
categorize让此函数返回一个多维数组，分类为第一维的键名，常量和它们的值位于第二维。
<?php
define("MY_CONSTANT", 1);
print_r(get_defined_constants(true));
?>
以上例程的输出类似于：
Array
(
[Core] => Array
(
[E_ERROR] => 1
[E_WARNING] => 2
[E_PARSE] => 4
[E_NOTICE] => 8
[E_CORE_ERROR] => 16
[E_CORE_WARNING] => 32
[E_COMPILE_ERROR] => 64
[E_COMPILE_WARNING] => 128
[E_USER_ERROR] => 256
[E_USER_WARNING] => 512
[E_USER_NOTICE] => 1024
[E_ALL] => 2047
[TRUE] => 1
)
[pcre] => Array
(
[PREG_PATTERN_ORDER] => 1
[PREG_SET_ORDER] => 2
[PREG_OFFSET_CAPTURE] => 256
[PREG_SPLIT_NO_EMPTY] => 1
[PREG_SPLIT_DELIM_CAPTURE] => 2
[PREG_SPLIT_OFFSET_CAPTURE] => 4
[PREG_GREP_INVERT] => 1
)
[user] => Array
(
[MY_CONSTANT] => 1
)
)
返回的数组为 常量名 => 常量值，也可以按注册变量的扩展名称来分组。
| 版本 | 说明 |
|---|---|
| 5.3.1 |
仅作用于 Windows：内核常量归类到 Core，之前是 mhash。
|
| 5.3.0 |
内核常量归类为 Core，之前是 internal。在 Windows 上，内核常量归类到 mhash。
|
| 5.2.11 |
categorize 参数现在可以合适得被处理。
在此之前，categorize 被解释为 !is_null($categorize)，导致任何非 null 的值会强制常量分类。
|
Example #1 get_defined_constants() 例子
<?php
print_r(get_defined_constants());
?>
以上例程的输出类似于：
Array
(
[E_ERROR] => 1
[E_WARNING] => 2
[E_PARSE] => 4
[E_NOTICE] => 8
[E_CORE_ERROR] => 16
[E_CORE_WARNING] => 32
[E_COMPILE_ERROR] => 64
[E_COMPILE_WARNING] => 128
[E_USER_ERROR] => 256
[E_USER_WARNING] => 512
[E_USER_NOTICE] => 1024
[E_ALL] => 2047
[TRUE] => 1
)
If you want to access directly on one category, just use:
<?php
print_r(get_defined_constants(true)['Core']);
?>
you can replace 'Core' by the category you wish (e.g. user):
<?php
print_r(get_defined_constants(true)['user']);
?>
Warning: only use this on development side
Add this method to your class definition if you want an array of class constants (get_defined_constants doesn't work with class constants as Peter P said above):
<?php
public function get_class_constants()
{
$reflect = new ReflectionClass(get_class($this));
return $reflect->getConstants());
}
?>
You could also override stdObject with it so that all your classes have this method
If you want to filter through and return only the prefix for your constants (i.e. you have constants with a naming scheme), then you can use this quick little function. It comes in handy for debugging.
<?php
function returnConstants ($prefix) {
foreach (get_defined_constants() as $key=>$value)
if (substr($key,0,strlen($prefix))==$prefix) $dump[$key] = $value;
if(empty($dump)) { return "Error: No Constants found with prefix '".$prefix."'"; }
else { return $dump; }
}
?>
Example:
<?php
define("SITENAME_OPTION_ONE",true);
define("SITENAME_OPTION_TWO",false);
define("SITENAME_URL","foo");
print_r(returnConstants("SITENAME_OPTION"));
?>
Will return:
Array
(
[SITENAME_OPTIONONE] => 1
[SITENAME_OPTIONTWO] =>
)
<?php
/**
* Convert constant value into string name.
*
* @param mixed Constant value.
* @return string Constant name.
* @access public
*/
function sch_get_consant($value)
{
$constants = get_defined_constants();
$name = array_search($value, $constants, TRUE);
return $name;
}
?>