<< Chapter < Page Chapter >> Page >


function body


In order for your class to identify which functions in an implementation section belong to it, you precede the function name in the function definition header with the class name and the scope resolution operator (::).

Access functions

Access to a class’ private data should be carefully controlled by the use of member functions, called access functions . For example, to allow clients to read the value of private data, the class can provide a get function.

To enable clients to modify private data, the class can provide a set function. Such modification would seem to violate the notion of private data. But a set member function can provide data validation capabilities (such as range checking) to ensure that the value is set properly. A set function can also translate between the form of data used in the interface and the form used in the implementation.

A get function need not expose the data in “raw” format; rather, the get function can edit data and limit the view of the data the client will see.


// time1.h

#if !defined(TIME1_H)

#define TIME1_H

class Time {


Time(); // constructor

void setTime( int, int, int ); // set hour, minute, second

void printMilitary(); // print military time format

void printStandard(); // print standard time format


int hour;

int minute;

int second;



// time1.cpp

#include “time1.h”


// Time constructor initializes each data member to zero.

// Ensures all Time objects start in a consistent state.

Time::Time() {

hour = minute = second = 0;


void Time::setTime( int h, int m, int s )


hour = ( h>= 0&&h<24 ) ? h : 0;

minute = ( m>= 0&&m<60 ) ? m : 0;

second = ( s>= 0&&s<60 ) ? s : 0;


void Time::printMilitary()


cout<<( hour<10 ? "0" : "" )<<hour<<":"

<<( minute<10 ? "0" : "" )<<minute;


void Time::printStandard()


cout<<( ( hour == 0 || hour == 12 ) ? 12 : hour % 12 )

<<":"<<( minute<10 ? "0" : "" )<<minute

<<":"<<( second<10 ? "0" : "" )<<second

<<( hour<12 ? " AM" : " PM" );


// Driver to test simple class Time

int main()


Time t; // instantiate object t of class Time

cout<<"The initial military time is ";


cout<<"\nThe initial standard time is ";


t.setTime( 13, 27, 6 );

cout<<"\n\nMilitary time after setTime is ";


cout<<"\nStandard time after setTime is ";


t.setTime( 99, 99, 99 ); // attempt invalid settings

cout<<"\n\nAfter attempting invalid settings:"

<<"\nMilitary time: ";


cout<<"\nStandard time: ";



return 0;


The output of the above program:

The initial military time is 00:00

The initial standard time is 12:00:00 AM

Military time after setTime is 13:37

Standard time after setTime is 1:27:06 PM

After attempting invalid settings:

Military time: 00:00

Standard time: 12:00:00 AM

In the above example, for the class Time we can see that member functions printStandard and printMilitary are two get function and member function setTime is a set function.

Constructor functions

A constructor function is a special function with the same name as its class. This function is called automatically when an object from a class is instantiated.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Programming fundamentals in c++. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10788/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Programming fundamentals in c++' conversation and receive update notifications?