Section 3 Define a Class [3]_PHP Tutorial

When you declare a class, you need to list all the variables and all the functions - called properties and methods - that the object should have. The composition of a class is shown in 3.1.1. Note that within curly brackets ({}) you can only Declare variables or functions. 3.1.2 shows how to define three properties and two methods in a class.

3.1.1
class Name extends Another Class
{
Access Variable Declaration
Access Function Declaration
} 3.1.2 //Define a class for tracking users
class User
{
//Attributes
public $name;
private $password, $lastLogin;

//Method
public function __construct($name, $password)
{
$this->name = $name;
$this->password = $password;
$this->lastLogin = time();
$this->accesses++;
}

// Get the time of the last access
function getLastLogin()
{
return(date("M d Y", $this->lastLogin));
}
}

//Create an instance of the object
$user = new User("Leon", "sdf123");

//Get the time of the last visit
print($user->getLastLogin() ."
n");

//Print user name
print("$user->name
n");
?> When you declare a property, you do not need to specify the data type. The variable may be an integer, a string, or another object, depending on the situation. It is a good idea to add comments when declaring properties, marking the meaning and data of the property. Type.

When you declare a method, you are doing the same as defining a function outside the class. Methods and properties have their own namespace. This means you can safely create a Methods with the same name as external functions will not conflict. For example, a class can define a method named date(). But you cannot name a method after a PHP keyword, such as for or while.

Class methods may contain what is called a type hint in PHP. A type hint is the name of another class that is passed arguments to the method. If your script calls a method and passes a variable that is not an instance of the class, PHP will generate a "fatal( fatal) error". You may not have given a type hint for other types, like integers, strings, or booleans. At the time of writing, it was controversial whether the type hint should include array types.

Type hints are a shortcut for testing the data type of function parameters or operator instances. You may always return this method. Make sure you force a parameter to be a data type, such as an integer. 3.2.1 Make sure the compiled class only produces Instance of Widget.

3.2.1 //Component
class Widget
{
public $name='none';
public $created=FALSE;
}

/ /Assembler
class Assembler
{
public function make(Widget $w)
{
print("Making $w->name
n");
$w->created=TRUE;
}
}

//Create a component object
$thing = new Widget;
$thing->name = 'Gadget ';

//Assembly component
Assembler::make($thing);
?> In addition to the variables passed to the parameters, methods contain a special variable. It represents an individual instance of the class. You should use this to point to properties and other methods of the object. Some object-oriented languages ​​assume that an unqualified variable is submitted to a local property, But any variable of a method in PHP is only within a certain scope of the method. Note the use of this variable in the constructor of the User class (3.1.2).

PHP defines an access point before the declaration of attributes and methods Qualifiers, such as public, private and protected. In addition, you can mark a member with "static". You can also declare constants in the class. There will be a discussion of different access methods later in this chapter.

You can list several properties with the same access method in one line, separating them with commas. In 3.1.2, the User class has two private properties-$password and $lastLogin.

http://www.bkjia.com/PHPjc/314107.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/314107.htmlTechArticleWhen you declare a class, you need to list all the variables and all the functions that the object should have - called properties and methods. The composition of a class is shown in 3.1.1. Note that within braces ({}) you can only pronounce...