7. C ++ class and encapsulation concept, 7. c encapsulation Concept

7. C ++ class and encapsulation concept, 7. c encapsulation Concept

Classes are generally divided into the following two parts:

• -ClassOfInternalImplementation
• -ClassOfExternalUsage

For example:

UserTo use a mobile phone, you only need to knowHow to Use.

WhileMobile phone developers, You need to consider the mobile phoneInternal implementationDetails.

 

 

Class Encapsulation

Not every member variable and member function of the class must be made public.

For example:

Girls do not want outsiders to know their weight and age

Boys don't want outsiders to know their height and salary

Some attributes are made public to the outside world.

For example:Name, education, nationality, etc.

Therefore, you can define the access level for the member variables and member functions in the class:

• -Public Public member,Allow member variables and member functions to be used inside and outside the class (public by default)
• -Private Private member, Can only be used inside the class

Scope of Class Members

The scope of all class members isOnly inside the class,External access failure

Member FunctionsYou can directlyAccess member variablesAndCall member functions

Class can be externalAccess public members through class variables

Class member'sScopeAndAccess LevelNo relationship

 

Refer to the following code:

# Include <stdio. h> int I = 1; // defines the global variable struct Test {private: int I; // defines the private member variable ipublic: int j; int getI () {I = 3; return I ;}; int main () {int I = 2; // defines the local variable I Test; test. j = 4; printf ("I = % d \ n", I); // I = 2; use the local variable printf (": I = % d \ n ",: I); //: I = 1; use the global variable // printf ("test. I = % d \ n ", test. i); // Error accessing the private member, Error printf ("test. j = % d \ n ", test. j); // test. j = 4 printf ("test. getI () = % d \ n ", test. getI ());
// Test. getI () = 3 access private member return 0 through public member ;}

 

Summary

Classes are generally dividedUsageAndInternal detailsTwo parts

Class encapsulation mechanism (Public/privateMake the usage and internal detailsPhase Separation