PHP Object-oriented? Static members

PHP Object-oriented? Static members

Static properties

Properties declared with the static keyword

The static property, logically, is the attribute defined above the class. guarantees a class that corresponds to a property.

Example:

Class Student

{

Public $stu _id;

Public $stu _name;

public static $stu _count = 0;

Public Function __constuct ($id, $name)

{

$this->stu_id = $id;

$this->stu_name = $name;

}
}

To access static properties:

Access by class: At the use of static accesses symbols (::)

Class:: Member

Example:

Class Student

{

Public $stu _id;

Public $stu _name;

public static $stu _count = 0;

Public Function __constuct ($id, $name)

{

$this->stu_id = $id;

$this->stu_name = $name;

Student:: $stu _count + +;

}
}

:: Access is called static access,-> for non-static access (object access)

When accessing a static property, if it is accessed within a class: You can use the Self current class

Example:

Class Student

{

Public $stu _id;

Public $stu _name;

public static $stu _count = 0;

Public Function __constuct ($id, $name)

{

$this->stu_id = $id;

$this->stu_name = $name;

Self:: $stu _count + +;

}
}

Note: The difference between $this and self

$this represents this object, and self indicates that the class

Static methods

The logical meaning of the static method is also the method of defining the re-class. Similarly, call form class::

Example:

Class Student

{

Public $stu _id;

Public $stu _name;

public static $stu _count = 0;

Public Function __constuct ($id, $name)

{

$this->stu_id = $id;

$this->stu_name = $name;

Self:: $stu _count + +;

}

public static function Saycount ()

{

echo "Run Static";

}
}

Student::saycount ();

The main difference between static and non-static methods is whether you can receive an object's execution environment.

Is whether the $this within the method can be assigned

Only when an object invokes a method can the object execution environment be passed into a method, $this is assigned a value.

Non-static properties cannot be used in static methods.

A static method that can handle only static data (static properties)

Example:

Class Student

{

Public $stu _id;

Public $stu _name;

public static $stu _count = 0;

Public Function __constuct ($id, $name)

{

$this->stu_id = $id;

$this->stu_name = $name;

Self:: $stu _count + +;

}

public static function Saycount ()

{

echo Self:: $stu _count;

}
}

Student::saycount ();

Special method access Issues in PHP:

Emphasis: Static methods should be called by the class, and non-static methods should be called by the object

Class C

{

Public Function F1 ()

{

Echo ' F1
’;

}

public static function F2 ()

{

Echo ' F2
’;

}

}

$o = new C;

$o->f1 ();

C::f2 ();

But:

1. Class access is available for both static and non-static methods: However, if a class statically invokes a non-static method, an error with a nonstandard syntax is reported.

2. The difference lies in the $this

You can use $this within a method only if you use the object to invoke a non-static method.

Class C

{

Public Function F1 ()

{

Echo ' F1
’;

}

public static function F2 ()

{

Echo ' F2
’;

}

}

C::F1 ();

C::f2 ();

Summary: The static and non-static methods of the class are only one copy of the class, but the runtime environment is different. You can use $this within a method only if you use the object to invoke a non-static method.

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