I. Class constants: Values that remain constant in a class are defined as constants
The constants of a class cannot use the access restriction modifier, which is public, inheritable, and can be overridden by a quilt
In the recent reading of the handbook, I found that PHP has a number of pits, a note will fall in, while looking at the content of these easy to confuse the record down.
Tips: It's best to look at the manual in English, because there are a number of things in the English manual that are not available in the Chinese manual (latest PHP)
PHP5.3 supports calling classes with a variable
PHP5.6 supports assigning values with an expression PHP类常量 andPHP静态属性
PHP7.1 suppor
, when the declaration does not assign values to data members, how can this happen? It is also important to note that declaring an enumeration in this way does not create a class data member, that is, when an object is created with this class, all objects do not contain an enumeration, months is just a symbolic name, a symbolic constant (not a variable), within the scope of the
: ', Self.name,self.value) print (' Other: ', Other.name,other.value) return NotImplementeda1 = A (' Tome ', 1) a2 = A (' Jim ', 1) print (a1 = = A2) #输出 # self:tome # other:jim # self:jim # other:to Me # FalseWhen you execute a1 = = A2 (that is, call __eq__ (A1,A2)), when you return to notimplemented, Python automatically switches the parameters to call __eq__ again (A2,A1)Five. Ellipsis1.Ellipsis is a constant of type ellipsist
PHP Object-Class constants
Class constants: In a class, save unchanged data in the running cycle.
Defined:
const keyword
const constant NAME = constant value
Example:
Class Student
{
Public $stu _id;
Public $stu _na
what is a class constant?
What we can understand in PHP is that the value is constant, so what is a class constant? In fact, the class constants are also easy to understand, we can always keep the constant value of the class is called
;Then there's a variable py in your memory, with a value of 6.88, and its type is float (floating point). You don't need to make any special statements before, and data types are automatically determined by Python.Here, we learned a built-in function type () that can query the type of the variable.ConstantsConstants are immutable variables, such as the commonly used number π, which is a constant. In Python, it is common to use all uppercase variable n
This article mainly introduces the PHP object-oriented programming and other constant usage, is a very important concept of PHP object-oriented programming, for PHP beginners are necessary to be firmly mastered, the need for friends can refer to the next
Class constants are a very important concept in PHP object-oriented programming, and a firm mastery of class
This article brings you the content is about how PHP through the path to get the file name (code), there is a certain reference value, the need for friends can refer to, I hope to help you.
Definition of a class constant
A constant defined inside a class.
Class constants must be defined with the Const keyword
Cons
is a simple call to create a member method.
Member variables
The variables in the class, also known as member variables, have been used in our previous examples. here we will introduce them to you.
Class Preson {public $ name; // defines the member variable public $ age ;}
In the above example, $ name is a member variable.
Class constant
If there are variables i
1. IdentifiersIdentifier: Used to represent the class name, variable name, method name, array name, valid character sequence of file nameIdentifiers by any order of letters, underscores such as: Name, User_age, $page identifier characters cannot be numeric identifiers cannot be reserved keywords in Java2. KeywordsHow many Java keywords (keyword) are there?51+2 a reserved word = 53 Keywords (java keywords are lowercase!!) )////////What is the reserved
Such as:public class innerclassdemo{int x;Class a{static int a = 0;//It is illegal to write this way.static final int b=0;//It's legal to write this}}
Java class load order, the class is loaded first, the static variable is initialized, and then the object is created, and if we want to execute the variable int a ini
PHP Object-oriented-class constants
PHP Object-oriented-class constants
Class constants: A class that holds unchanged data for the duration of a run.
Defined:
const keyword
const cons
Constants that need to be made public are placed in the header file, and constants that do not need to be made public are placed in the header of the definition file. For ease of management, constants of different modules can be stored in a public header file.
1>Constant member of the class, as follows:
The const data
Such as:public class innerclassdemo{int x;Class a{static int a = 0;//is not legal to write this way.static final int b=0;//It's legal to write this.}}Answer: to put it simply, define a static domain or method that requires a static environment or a top-level environment, where the static environment specifically says that if you add static Class A In your example
Code code as follows:
Static methods instance (static Method Example)
Class Foo
{public static function Astaticmethod () {}
}
Foo::astaticmethod ();
?>
You can define constants in each base class to keep it unchanged. Constants differ from ordinary variables when you do not use the $ symbol t
Such as:public class innerclassdemo{int x;Class a{static int a = 0;//is not legal to write this way.static final int b=0;//It's legal to write this.}}Java class loading order, first load the class, execute the static variable initialization, and then execute the object creation, if we want to execute the code in the va
variable name or the value of the variable), when the reference count is 0, meaning that the object has not been used ~
Del statementThe DEL statement deletes a reference to the object, del Syntax: Del obj[, obj2[, ... Objn]]del xtwo actions after execution:1) Delete x from the current namespace2) The reference count of the object pointed to by X minus 1
Garbage collection mechanism
The Python GC module tracks and reclaims garb
Class foo{
Const Con_var= "The value of the constant property cannot be modified";
Public Function method_a () {
Echo (Self::con_var);
}
}
Echo (Foo::con_var);
$myFoo =new Foo ();
Echo ($myFoo->method_a ());
?>
Copy CodeNote: Constant properties cannot use object access, only class access, within the class
Php object-oriented-class Constants
Php object-oriented-class Constants
Class constant: in the class, data that remains unchanged during the running period is saved.
Definition:
Const keyword
Const constant name = constant value
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