Attributes and class methods in PHP5 classes_PHP tutorial
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2016-07-13 17:15:00896browse
This article introduces in detail the attributes and class methods in PHP5 classes. Friends who need to learn can refer to the information.
PHP5 class methods
Process: A process is a sequence of statements defined when programming to complete a specified operation.
Function: A function has a return value and is also a defined sequence of statements.
Method: In the object-oriented concept, a sequence of statements in a class.
Generally speaking, in object-oriented concepts, the two terms function and method are common.
Read attributes through methods
The following example sets the property to private and declares the public getName() method to obtain the value of the property $name. Calling the getName() method will return the value of $name through return $this->name.
The code is as follows
Copy code
代码如下
复制代码
class Person
{
private $name = “NoName”; //private成员$name
public function getName() {
return $this->name;
}
}
$newperson = new Person();
echo ” ” . $newperson->getName();
?>
class Person
{
private $name = “NoName”; //private member $name
public function getName() {
return $this->name;
}
}
代码如下
复制代码
class Person
{
private $a;
function setA($_a) {
$thia->a = $_a;
}
function getA() {
return $this->a;
}
}
$newperson = new Person();
$newperson->setA(100);
echo $newperson->getA();
?>
$newperson = new Person();
代码如下
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class A
{
public $name = “tom”;
}
class Person
{
private $a;
function setA($_a) {
$this->a = $_a;
}
function getA() {
return $this->a;
}
}
$a1 = new A();
$p = new Person();
$p->setA($a1);
echo $p->getA()->name;
?>
echo ” ” . $newperson->getName();
?>
Note: Here, when calling local properties inside the method, use $this->name to get the properties. In this example, the public getName() method is set, that is, the user can only obtain $name, but cannot change its value. This is the benefit of encapsulation.
Encapsulation refers to the mechanism that bundles the state information (properties) and behavior (methods) of an object into a logical unit.
In PHP5, data is encapsulated and declared as private, and then one or more public methods are provided to operate the attribute to achieve the following purposes:
Prevent unauthorized access to encapsulated data. Users can only access data through pre-customized methods, and can easily add control logic to limit unreasonable operations on attributes;
Helps ensure data integrity;
Easy to modify and enhance the maintainability of the code;
Method parameters
Variables can be passed inside the method through parameters when the method is defined.
In line 5 below, the method parameter $_a is defined when defining the method. When using this method, you can pass parameter variables into the method. Variables received within a method are local variables and are only valid within the method. You can apply a variable to the entire object by passing its value to a property.
If this method is declared to have parameters and no parameters are passed when calling this method, or the number of parameters is insufficient, the system will report an error. If the number of parameters exceeds the number of parameters defined by the method, PHP will ignore the excess parameters and will not report an error. Default values can be set for parameters when the function is defined. When calling the method, if no parameters are passed, this parameter variable will be filled with default values.
Usage of attributes: Call the attribute of the object pointed to by the variable by referencing the -> symbol of the variable.
Call a property of the same object inside a method via the $this-> notation.
The code is as follows
代码如下
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class Person
{
public $name = “NoName”; //定义public属性$name
public $age = 20; //定义public属性$age
}
$p = new Person(); //创建对象
echo ” ” . $p->name; //输出对象$p的属性$name
echo “ ”;
echo ” ” . $p->age; //输出$age属性
?>
Copy code
class Person
{
public $name = “NoName”; //Define public attribute $name
代码如下
复制代码
class Person
{
public $name = “NoName”; //公共变量$name
public $age = 20; //公共变量$age
}
$p = new Person();
$p->name = “Tom”; //我是Tom
$p->age = 25 ; //年龄25
echo ” ” . $p->name; //输出名字
echo “ ”;
echo ” ” . $p->age; //年龄
?>
public $age = 20; //Define public attribute $age
}
$p = new Person(); //Create object
echo ” ” . $p->name; //Output the attributes of object $p $name
echo “ ”;
echo ” ” . $p->age; //Output $age attribute
?>
Attributes in PHP5 classes
We can also change the value of the attribute. Of course, it should be noted that changing the value of the attribute is modified through public
Let’s modify this example:
The code is as follows
Copy code
class Person
{public $name = “NoName”; //Public variable $namepublic $age = 20; //Public variable $age}$p = new Person();$p->name = “Tom”; //I am Tom
$p->age = 25; //Age 25
echo ” ” . $p->name; //Output name
echo “ ”;
echo ” ” . $p->age; //Age
?>
Create a Person object and change the properties of this object. Name it and see its name. You are the god of the Person object in the machine. According to the rules you defined, this real Person object in memory is created, and it has properties that can be changed.
Initial value of attribute
In PHP5, you can not set an initial value in the attribute definition, or assign the following red type initial value.
There are 8 simple types in PHP, namely:
Four scalar types:
Boolean
integer
Float (floating point number, also called "double")
String
Two compound types:
Array
Object
Finally there are two special types:
resource
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