PHP Object-oriented summary

Class

Sum up a few words

:

①

Classes are abstract and represent a class of things

Ii

object is specific and is a concrete instance of a class

③

Class is a template for an object

,

An object is an individual instance of a class

Construction method

?

Construction method

No return value

,

It is automatically called

2.

In

PHP 5

In a class can have both

Two forms of construction method

__construct ()

And

Class name

() ,

When two exist at the same time, the first call

__construct (),

Please use after everyone

__construct ()

?

1. $this

It's the address of the object that can be understood.

2.

Which object is used to

$this,

is which object address

3. $this

Cannot be used outside the class

.

Can only be used within a class

Considerations for construction methods

(1)

Once a constructor has been customized, the default

The constructor is overwritten.

,

When you create an object, you will use a custom

constructor function

.

(2)

A class can have only one constructor

. (

Cannot reload

)

of the construction method

8

Point description

:

① constructor method name and class name are the same

(PHP4

Version

), PHP5

Version of the construction method

The name can be the same as the class name, or it can be

__construct () (PS:

Two

_)

PHP Object-oriented summary