PHP Object-Oriented Programming-Constructor

The basic syntax for customizing constructor methods in the class:

 
// PhP5
[Modifier] function _ construct ([parameter list]) {}
// PhP4
 

 
[Modifier] function class name ([parameter list]) {}

Reading a column is easy to understand:
 

<? PHP  Class  Person {  Public   $ Name  ;  Public   $ Age  ;  //  Constructor PhP5          Public  Function _ Construct ( $ Name , $ Age  ){  $ This -> Name = $ Name  ;  $ This -> Age = $ Age  ;}  //  The constructor PhP4 is written here as PhP5 is compatible with PhP4.          Public   Function Person ($ Name , $ Age  ){  $ This -> Name = $ Name  ;  $ This -> Age = $ Age  ;}}  $ P1 = New Person ("boss", 27 );  Echo   $ P1 ->Name;  $ P1 = New Person ("xiao'er", 26 );  $ P1 = New Person ("John", 24 ); ?>

Note:

$ This:

1. $ this is essentially the address of this object.

2. Which object is $ this, which is the object address?

3. $ this cannot be used outside the class Understanding of constructor:

• The constructor name and class name are the same (PhP4) and PhP5 ConstructorThe name can be the same as the class name or _ construct ()
• The default access modifier of the constructor is public, and the constructor does not return a value.
• After a new object is created, the system automatically calls the constructor of this class.
• A class has only one constructor. After PhP5, although _ construct () and Class Name () can coexist, only one construct () can be used.
• For exampleIf no custom constructor is provided for the class, the class uses the default constructor..
• If a constructor is defined for the class, the default constructor of the class is overwritten.