PHP object-oriented (i)

Last Update:2016-07-07 Source: Internet

Author: User

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first, the Concept:The full version of PHP5 introduces an all-object-oriented Mechanism.Object-oriented programming (OOP): When a computer program is composed of a single unit or object that can function, each object can receive information, process data, and send information to other objects in order to achieve the overall Operation.object-oriented three goals: reusability, flexibility, and Extensibility.object-oriented features: encapsulation, inheritance, and Polymorphism.Class: is a stand-alone program unit that is a collection of a set of objects that have the same properties and Services. Its internals include the member properties and methods of the service two main sections.Object: an entity used to describe an objective thing in a system, which is a basic unit of a System. An object consists of a set of properties and a set of services that are authorized to operate on those Properties.II. Declaration of Class: keyword classSyntax format:[modifier] class Name { Member properties define variables"member methods" Define Functions }<pre>1<?PHP2 classStudent3 {4 //Defining member Properties5 public $name;6 public $age;7 //Defining member Methods8 public functionSayHello ()9 {Ten Echo"Hello world!"; one } a - } -?></pre>Iii. Instantiation of objectsSyntax format: $ variable name = new class name ([parameter list]);Or: $ Variable name = new Class name;<pre>1<?PHP2 classStudent3 {4 //Defining member Properties5 public $name;6 public $age;7 //Defining member Methods8 public functionSayHello ()9 {Ten Echo"Hello world!"; one } a - } - the //instantiation of two students - $stu 1=NewStudent (); - $stu 2=NewStudent; - +?></pre>Allocation of object types in Memory:1) stack space segment: the feature is small space, but the speed of access by the cpu, used to store the temporary variables created in the Program. Because of the last-in-first-out feature of the stack, the stack is particularly handy for saving and recovering call Sites. "double, Boolean"2) Heap Space segment: The heap is used to store dynamically allocated memory segments in the process running, which are not fixed and can be dynamically expanded or scaled to store data with variable length or large memory size. "string, array, object"3) Initialize the data segment: used to hold the initialized global variables in the executable file, in other words, to store variables statically allocated by the Program.4) code snippet: The operation instruction used to hold the executable, that is, it is an image of the executables in Memory. Code snippets need to be prevented from being modified illegally while running, so only read operations are allowed, not write (modify) operations.Object type data is a large space-occupying data type, and is a variable-length data type, so when the object is created, it is in heap memory, but the Object's reference name is stored in the STACK.Iv. member access in objectsObjects contain member properties and member methods, and access to members in an object includes access to member properties and member METHODS. Special operator, "-" to complete access to object Members.Syntax format:$ Reference name = new class name ([parameter list]);$ reference name, member property = value;echo $ reference name, member property;$ reference name, member method;<pre>1<?PHP2 classStudent3 {4 //Defining member Properties5 public $name;6 public $age;7 //Defining member Methods8 public functionSayHello ()9 {Ten Echo"Hello world!"; one } a - } - the //instantiation of - $stu 1=NewStudent (); - $stu 2=NewStudent; - + $stu 1->name = "zhang san"; - $stu 1->age = 20; + Echo"my name Is: {$stu 1->name} this year {$stu 1->age} years old! "; a $stu 1-SayHello (); at -?></pre>Special Object References: $thisOnce an object is created, there is a special object reference "$this" in each member method in the Object. Which object the member method belongs to, $this represents which object, which is specifically used to complete access between members of the internal Object.<pre>1<?PHP2 classStudent3 {4 //Defining member Properties5 public $name;6 public $age;7 //Defining member Methods8 public functionSayHello ()9 {Ten Echo"my name Is: {$this->name} this year {$this->age} years old! Hello world! "; one a } - - } the - //instantiation of - $stu 1=NewStudent (); - $stu 2=NewStudent (); + - $stu 1->name = "zhang san"; + $stu 1->age = 20; a $stu 1-SayHello (); at - $stu 1->name = "john doe"; - $stu 1->age = 22; - $stu 1-SayHello (); - -?></pre>Construction method and method of destructionConstruction methods and destructors are two special methods in objects that are related to the life cycle of an object. The constructor method is the first method that is automatically called by the object after the object is created, and the destructor is the last method that the object is automatically called by the object before it is Destroyed.1) Construction MethodWhen an object is created, the constructor is automatically called once, that is, each time the object is instantiated with the keyword new, The construction method is called automatically, and the constructor method cannot be invoked actively through the Object's reference. So the construction method is generally used to initialize the Task. The constructor method name must be "__construct ()". (PHP5 change, before PHP5 version, The constructor method must be the same as the class name, PHP5 is still Available)Syntax format:function __construct ([parameter List])//constructor method name is __construct () starting with two underscores{#方法体 is typically used to assign an initial value to a member variable}2) destructor methodThe method that corresponds to the construction method is the destructor, and PHP will call this automatically before the object is Destroyed. Destructors allow certain actions to be performed before destroying an object, such as closing a file, releasing a result set, and so On. The destructor method name is "__destruct ()", and the destructor cannot have any parameters.Syntax format:function __destruct ()//destructor name is a __destruct () starting with two underscores{#方法体 is typically used to perform cleanup tasks before objects are destroyed}<pre>1<?PHP2 classStudent3 {4 public $name;5 public $age;6 7 //constructs the method, which is automatically called when new is instantiated, to implement object initialization assignments8 public function__construct ($name,$age)9 {Ten $this->name=$name; one $this->age=$age; a } - - public functionGetInfo () the { - Echo"my name:".$this->name. "gender:".$this->age. " "; - } - + public function__destruct () - { + Echo"this is a Destructor. "; a Echo $this->name. " The object is released! "; at } - } - - - - //instantiation of in $zhangsan=NewStudent ("zhang san", 20); - $lisi=NewStudent ("john doe", 22); to + $zhangsan-GetInfo (); - $lisi-GetInfo (); the * $?></pre>PHP object-oriented (i)

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