(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
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));
?>以上示例的输出类似于：
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。
示例 #1 get_defined_constants() 示例
<?php
print_r(get_defined_constants());
?>以上示例的输出类似于：
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
)
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 $reflect->getConstants());
}
?>
You could also override stdObject with it so that all your classes have this methodIf you want to access directly on one category, just use:
<?php
print_r(get_defined_constants(true)['Core']);
?>
you can replace 'Core' by the category you wish (e.g. user):
<?php
print_r(get_defined_constants(true)['user']);
?>
Warning: only use this on development sideIf you want to filter through and return only the prefix for your constants (i.e. you have constants with a naming scheme), then you can use this quick little function. It comes in handy for debugging.
<?php
function returnConstants ($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;
}
?>