PHP object-oriented programming and other constant usage examples, sed usage examples

PHP object-oriented programming and other constant usage examples, sed usage examples

Class constants are a very important concept in PHP object-oriented programming. A strong grasp of class constants will help to further improve the level of PHP object-oriented programming. This article describes the usage of class constants in PHP programming as an example. The details are as follows:

Class constant: in the class, data that remains unchanged during the running period is saved.

Definition:

Const keyword const constant name = constant value

Example:

Class Student {public $ stu_id; public $ stu_name; public $ stu_gender; const GENDER_MALE = 'male'; const GENDER_FEMALE = 'femal ';}

Class constants are not restricted by access modifiers.
Access Method:
Class: constant name

Example:

Class Student {public $ stu_id; public $ stu_name; public $ stu_gender; const GENDER_MALE = 'male'; const GENDER_FEMALE = 'feme'; public function _ construct ($ id, $ name, $ gender = '') {$ this-> stu_id = $ id; $ this-> stu_name = $ name; $ this-> gender = ($ gender = '')? Self: GENDER_MALE: $ gender ;}}

Summary:The following elements can be defined in a class: constants, static attributes, non-static attributes, static methods, and non-static methods..

Note:
$ This indicates the current object. Does it always represent the object of the class where $ this is located?
The answer is no! Because the value of $ this does not depend on the class where $ this is located, but on the execution object (Execution Environment) when the $ this method is called)

The execution environment of the method. The $ this in the method indicates the object in which the current method is executed.

What is php object-oriented programming?

Object-Oriented Programming (OOP) is designed to create software to reuse code and better simulate real-world environments, this makes it recognized as the winner of top-down programming. It adds an extension statement to the program to encapsulate the function into the "object" necessary for programming. The object-oriented programming language makes complex work organized and easy to write

What problems does final constants occur in object-oriented programming?

Final constants indicate that they cannot be modified, that is, they are equivalent to constants in C language.

The final function is not allowed to be overwritten after being inherited.

If the final ID is not used, no error will be reported if it is changed, and the stability of the program will be affected.