PHP 语言参考 | Language Reference 目录 != !== & ++ -- << <=> <> =& == === >> abstract and Anonymous (class)es Anonymous functions Arithmetic Operators Array Operators Arrays Assignment Operators Autoloading Classes Basics Basics Basics Bitwise Operators Booleans Callbacks / Callables catch Class Abstraction Class Constants clone Comments Comparing generators with Iterator objects Comparing Objects Comparison Operators Constants Constructors and Destructors Declaring sub-namespaces Defining multiple namespaces in the same file Defining namespaces Error Control Operators Errors Errors in PHP 7 Escaping from HTML Exceptions Execution Operators Expressions Extending Exceptions extends FAQ: things you need to know about namespaces final Final Keyword finally Floating point numbers function Function arguments Generator syntax Generators overview Global space implements Incrementing/Decrementing Operators instanceof Instruction separation Integers interface Internal (built-in) functions Introduction Iterables Late Static Bindings Logical Operators Magic constants Magic Methods Name resolution rules namespace keyword and __NAMESPACE__ constant Namespaces and dynamic language features Namespaces overview NULL Object Cloning Object Inheritance Object Interfaces Object Iteration Object Serialization Objects Objects and references OOP Changelog Operator Precedence Operators or Overloading Passing by Reference PHP tags Predefined Variables private Properties protected Pseudo-types and variables used in this documentation public Resources Returning References Returning values Scope Resolution Operator (::) Spotting References static Static Keyword String Operators Strings Superglobals Syntax trait Traits try Type Hinting Type Juggling Type Operators Unsetting References User-defined functions Using namespaces: Aliasing/Importing Using namespaces: Basics Using namespaces: fallback to global function/constant Variable scope Variable variables Variables From External Sources Visibility What References Are What References Are Not What References Do xor yield ^ __clone() __construct() __destruct() | ~