php--得到我们开始使用php前的一些参数：变量 / 常量 / 模块 / 函数 / 类

1,array get_defined_vars ( void )获取由所有已定义变量所组成的数组(包括环境变量、服务器变量和用户定义的变量。)

2,array get_defined_functions ( void ) 获取所有已经定义的函数

3,array get_loaded_extensions ([ bool $zend_extensions = false ] )返回了 PHP 解析器里所有编译并加载的模块名。

参数默认是false，返回（普通扩展和zend扩展），true时只返回zend扩展。

4，array get_extension_funcs ( string $module_name )返回指定模块所有可用的函数

5，array get_defined_constants ([ bool $categorize = false ] )返回所有常量的关联数组，键是常量名，值是常量值

6，array get_declared_classes ( void )获取由已定义类的名字所组成的数组

7，get_included_files() / get_require_files() 返回所有被 include、 include_once、 require 和 require_once 的文件名，组成数组，第一个是本文件名。

看一下，discuz！3.x的forum.php载入了多少文件：

Array(    [0] => D:\webserver\www\Discuz_X3.1\forum.php    [1] => D:\webserver\www\Discuz_X3.1\source\class\class_core.php    [2] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_application.php    [3] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_base.php    [4] => D:\webserver\www\Discuz_X3.1\source\function\function_core.php    [5] => D:\webserver\www\Discuz_X3.1\config\config_global.php    [6] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_database.php    [7] => D:\webserver\www\Discuz_X3.1\source\function\function_forum.php    [8] => D:\webserver\www\Discuz_X3.1\source\class\db\db_driver_mysql.php    [9] => D:\webserver\www\Discuz_X3.1\source\class\table\table_common_syscache.php    [10] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_table.php    [11] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_memory.php    [12] => D:\webserver\www\Discuz_X3.1\source\class\table\table_common_member.php    [13] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_table_archive.php    [14] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_session.php    [15] => D:\webserver\www\Discuz_X3.1\source\class\table\table_common_session.php    [16] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_cron.php    [17] => D:\webserver\www\Discuz_X3.1\source\class\table\table_common_cron.php    [18] => D:\webserver\www\Discuz_X3.1\source\class\discuz\discuz_process.php    [19] => D:\webserver\www\Discuz_X3.1\source\class\table\table_common_process.php    [20] => D:\webserver\www\Discuz_X3.1\source\include\cron\cron_follow_daily.php    [21] => D:\webserver\www\Discuz_X3.1\source\class\table\table_home_follow_feed.php    [22] => D:\webserver\www\Discuz_X3.1\source\class\helper\helper_util.php    [23] => D:\webserver\www\Discuz_X3.1\source\language\lang_core.php    [24] => D:\webserver\www\Discuz_X3.1\source\plugin\mobile\mobile.class.php)

载入了这么多还真吓人。

总结，php在我们使用之前已经有这么多参数，有点小惊讶，特别是有一百多个类：

Array(    [0] => stdClass    [1] => Exception    [2] => ErrorException    [3] => COMPersistHelper    [4] => com_exception    [5] => com_safearray_proxy    [6] => variant    [7] => com    [8] => dotnet    [9] => ReflectionException    [10] => Reflection    [11] => ReflectionFunctionAbstract    [12] => ReflectionFunction    [13] => ReflectionParameter    [14] => ReflectionMethod    [15] => ReflectionClass    [16] => ReflectionObject    [17] => ReflectionProperty    [18] => ReflectionExtension    [19] => DateTime    [20] => DateTimeZone    [21] => LibXMLError    [22] => __PHP_Incomplete_Class    [23] => php_user_filter    [24] => Directory    [25] => SimpleXMLElement    [26] => DOMException    [27] => DOMStringList    [28] => DOMNameList    [29] => DOMImplementationList    [30] => DOMImplementationSource    [31] => DOMImplementation    [32] => DOMNode    [33] => DOMNameSpaceNode    [34] => DOMDocumentFragment    [35] => DOMDocument    [36] => DOMNodeList    [37] => DOMNamedNodeMap    [38] => DOMCharacterData    [39] => DOMAttr    [40] => DOMElement    [41] => DOMText    [42] => DOMComment    [43] => DOMTypeinfo    [44] => DOMUserDataHandler    [45] => DOMDomError    [46] => DOMErrorHandler    [47] => DOMLocator    [48] => DOMConfiguration    [49] => DOMCdataSection    [50] => DOMDocumentType    [51] => DOMNotation    [52] => DOMEntity    [53] => DOMEntityReference    [54] => DOMProcessingInstruction    [55] => DOMStringExtend    [56] => DOMXPath    [57] => RecursiveIteratorIterator    [58] => IteratorIterator    [59] => FilterIterator    [60] => RecursiveFilterIterator    [61] => ParentIterator    [62] => LimitIterator    [63] => CachingIterator    [64] => RecursiveCachingIterator    [65] => NoRewindIterator    [66] => AppendIterator    [67] => InfiniteIterator    [68] => RegexIterator    [69] => RecursiveRegexIterator    [70] => EmptyIterator    [71] => ArrayObject    [72] => ArrayIterator    [73] => RecursiveArrayIterator    [74] => SplFileInfo    [75] => DirectoryIterator    [76] => RecursiveDirectoryIterator    [77] => SplFileObject    [78] => SplTempFileObject    [79] => SimpleXMLIterator    [80] => LogicException    [81] => BadFunctionCallException    [82] => BadMethodCallException    [83] => DomainException    [84] => InvalidArgumentException    [85] => LengthException    [86] => OutOfRangeException    [87] => RuntimeException    [88] => OutOfBoundsException    [89] => OverflowException    [90] => RangeException    [91] => UnderflowException    [92] => UnexpectedValueException    [93] => SplObjectStorage    [94] => XMLReader    [95] => XMLWriter    [96] => mysqli_sql_exception    [97] => mysqli_driver    [98] => mysqli    [99] => mysqli_warning    [100] => mysqli_result    [101] => mysqli_stmt    [102] => PDOException    [103] => PDO    [104] => PDOStatement    [105] => PDORow)

8 ，get_class_methods(class name);//取得class name 类的所有的方法名，并且组成一个数组