get_declared_classes()

(PHP 4, PHP 5, PHP 7)

返回由已定义类的名字所组成的数组

说明

返回由当前脚本中已定义类的名字组成的数组。

返回值

返回由当前脚本中已定义类的名字组成的数组。

需要注意的是额外类的出现依赖于你已编译到 PHP 中的库。这意味着你不能使用这些类名定义自己的类。在附录的预定义类部分有预定义类的列表。

范例

Example #1get_declared_classes()例子

以上例程的输出类似于：

Array
(
    [0] => stdClass
    [1] => __PHP_Incomplete_Class
    [2] => Directory
)

参见

• class_exists()检查类是否已定义
• get_declared_interfaces()返回一个数组包含所有已声明的接口
• get_defined_functions()返回所有已定义函数的数组

The array returned by this function will be in the order the classes were defined / included / required and this order does not appear to change.
For example:

Output:
Array
( 
  [0] => stdClass
  [1] .... other defined classes....
  [10] => classone
  [11] => classtwo
 )
and...
Array
( 
  [0] => stdClass
  [1] .... other defined classes....
  [10] => classone
  [11] => classtwo
  [12] => classthree
  [13] => classfour
)

Regarding note of 3-21:

This function could also be used to determine the names of classes defined in a particular file by calling it before and after include. It's hardly a pointless function.

get-declared-classes makes no sense at all, if u maybe, later for production, merge class files in one package file. 
lets say: package.php
print_r(get_declared_classes());
class declaredHere { }
print_r(get_declared_classes());
so in this case, the declaredHerr class is defined at the first call of print_r();
because PHP-complier runs a hole file and declare Stuff before running the code.
But (Lovely PHP):
print_r(get_declared_classes());
if(true){
class declaredHere { }
}
print_r(get_declared_classes());
Will print the declaredHere class only in the second print_r.
Its not a Bug it a...

Summary:
 * in PHP 5.1 class names have case preserved
 * contrary, in PHP 4.4 class names are downcased, withe exception of a few build-in ones
The get_declared_classes() funcition returns the list of names with case preserved, as of PHP 5.1 series (prolly 5.0 too, but i have no way to test it right now). Since PHP generally is caseless in regard to names of classes, this may come at a surprise. Also, this could potentially break older code asssuming downcased list.
Take extra care when checking for existence of a class. Following example is, potentially, error prone: 
A sure-fire (while slower) way would be to iterate over the array and normalize case to, say, lower:

Optimization of the above snippet is left as a simple excercise to the reader ;)
-- dexen deVries

classes can't be unloaded. probably not very practical to implement that in a future version. I wouldn't go out of my way to do it if I were zend. you're better off finding a workaround. it's better programming technique to find a way around having to do that anyway.
http://www.zend.com/zend/week/week223.php#Heading10

you cannot remove them. they are "defined", which happens when the class is being loaded from the parser. you just deleted an instance of a class.

This function considers only classes and subclasses. Not subsubclasses.
In fact I have code that provides an abstract class and then classes using this abstract class. Further I have subclasses to my concrete classes - which is why my subclasses are not listed within the returned array.

In PHP5, you don't get declared interfaces by calling this function!!!
To get interfaces you should use get_declared_interfaces(). However, to check if an interface is already defined, you should use class_exists()! This is strange, but PHP team does not think so.

those above comments are too old.
now, whatever the order is, the output will be the same:

will output the same result.