PHP object-oriented constants in PHP5_PHP tutorial

In PHP5, constants defined by const are different from the methods of defining variables, and do not need to be added with the $ modifier. const PI = 3.14; This will do.
Constant names defined using const are generally capitalized. This is a convention and is the same in any language.
If the defined constant consists of multiple words, use _ to connect them. This is also the convention.
For example, naming like MAX_MUMBER. A good naming method is something that programmers must pay attention to.
Constants in a class are similar to static variables, except that their value cannot be changed. We use classname::constantname to call this constant.

Copy code The code is as follows:

<?
//Declare a final class Math
class Math{
const PI = 3.14; public function __toString(){
return “This is the Math class.”; Method. Const constants are used,
//Note the method used, similar to static variables.
public final function areaOfCircular($r){
return $r * $r * self::PI ;
} Public Final Function Max ($ a, $ B) {
Return $ A & GT; PI ;
?>


Program running result:



Copy code

The code is as follows:

3.14

If you try to assign a value to a constant defined by const, an error will occur.

Copy code

The code is as follows:

<?//Declare a final class Mathclass Math { const PI = 3.14; public function __toString(){

return "This is the Math class.";

}
//A method for calculating the area of ​​a circle is written here. Use Const constant,
//Note the method used, similar to static variables.
public final function areaOfCircular($r){
return $r * $r * self::PI ;
}
public final function max($a,$b){
return $a > $b ? $a : $b ;
}
public function setPI($a){
self::PI = 3.1415;
}
}
echo Math::PI ;
?>


Program running result:



Copy code

The code is as follows:

Parse error: parse error in E:PHPProjectstest.php on line 17

http://www.bkjia.com/PHPjc/321644.html

www.bkjia.com

true

http: //www.bkjia.com/PHPjc/321644.htmlTechArticleThe constants defined by const in PHP5 are different from the methods of defining variables, and do not need to be added with the $ modifier. const PI = 3.14; This will do. Constant names defined using const are generally in uppercase letters, this...