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The public access specifier allows anyone to call a class’s function member or to modify a data member.

The private access specifier is one of the key elements in information hiding since it prevents clients from calling member functions or accessing data members.

Both public and private specifiers have what is called class scope : class members of both access types are accessible from any of a class’s member functions.

Example:

class Time {

public:

Time();

void setTime( int, int, int );

void printMilitary();

void printStandard();

private:

int hour;

int minute;

int second;

};

Note that the data members hour, minute, and second are preceded by the private member access specifier. A class’ private data members are normally not accessible outside the class. The philosophy here is that the actual data representation used within the class is of no concern to the class’ clients. In this sense, the implementation of a class is said to be hidden from its clients. Such information hiding promotes program modifiability and simplifies the client’s perception of a class.

You can depict the classes graphically in a class diagram as below.

Diagram of class Time

The diagram shown above follows the format of the Unified Modeling Language (UML). Each class is represented by a box, with the class name in the top portion of the box, any data members that you care to describe in the middle portion of the box, and the member functions (the functions that belong to this object, which receive any messages you send to that object) in the bottom portion of the box.

Interface and implementation files

Although the first step in information hiding is to assign private access specifiers to class members, private access specifiers only designate which class members a client is not allowed to call or change. Private access specifiers do not prevent clients from seeing class code. To prevent clients from seeing the details of how your code is written, you place your class’s interface code and implementation code in separate files.

The separation of classes into separate interface and implementation files is considered to be a fundamental software development technique since it allows you to hide the details of how your classes are written and makes it easier to modify programs.

The interface code refers to the data member and function member declarations inside a class’s braces. Interface code does not usually contain definitions for function members, nor does it usually assigns values to the data members. You create interface code in a header file with an .h extension.

The implementation code refers to a class’s function definitions and any code that assigns values to a class’s data members. In other words, implementation code contains the actual member functions themselves and assigns values to data members. You add implementation code to standard C++ source files with an extension of .cpp.

As far as clients of a class are concerned, changes in the class’ implementation do not affect the client as long as the class’ interface originally provided to the client is unchanged. All that a client needs to know to use the class correctly should be provided by the interface.

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Programming fundamentals in c++. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10788/1.1
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