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
)