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where the new_type portion is the keyword representing the type to which you want to cast the variable.

Example:

int iNum = 100;

float fNum;

fNum = float (inum);

If you do not explicitly cast a variable of one data type to another data type, then C++ will try to automatically perform the cast for you.

Program input using the cin object

So far, our programs have been limited in the sense that all their data must be defined within the program source code.

We will now learn how to write programs which enable data to be entered via the keyboard, while the program is running.

Such programs can be made to operate upon different data every time they run, making them much more flexible and useful.

Standard input stream

The cin object reads in information from the keyboard via the standard input stream.

The extraction operator (>>) retrieves information from the input stream.

When the statement cin>>num1; is encountered, the computer stops program execution and accepts data from the keyboard. The user responds by typing an integer (or float) and then pressing the Enter key (sometimes called the Return key) to send the number to the computer. When a data item is typed, the cin object stores the integer (or float) into the variable listed after the>>operator.

The cin and cout stream objects facilitate interaction between the user and the computer. Because this interaction resembles a dialogue, it is often called conversational computing or interactive computing.

Example

#include<iostream.h>

int main()

{

int integer1, integer2, sum; // declaration

cout<<"Enter first integer\n"; // prompt

cin>>integer1; // read an integer

cout<<"Enter second integer\n"; // prompt

cin>>integer2; // read an integer

sum = integer1 + integer2;

cout<<"Sum is "<<sum<<endl;

return 0; // indicate that program ended successfully

}

The output of the above program:

Enter the first integer

45

Enter the second integer

72

Sum is 117

Example

#include<iostream.h>

int main()

{

int integer1, integer2, sum; // declaration

cout<<"Enter two integers\n"; // prompt

cin>>integer1>>integer2; // read two integers

sum = integer1 + integer2;

cout<<"Sum is "<<sum<<endl;

return 0;

}

The output of the above program:

Enter two integers

45 72

Sum is 117

Symbolic constants

C++ introduces the concept of a named constant that is just like a variable, except that its value cannot be changed. The qualifier const tells the compiler that a name represents a constant. Any data type, built-in or user-defined, may be defined as const. If you define something as const and then attempt to modify it, the compiler will generate an error.

To define a constant in a program, we use const declaration qualifier.

Example:

const float PI = 3.1416;

const double SALESTAX = 0.05;

const int MAXNUM = 100;

Once declared, a constant can be used in any C++ statement in place of the number it represents.

Example

// this program calculates the circumference of a circle

// given its radius

#include<iostream.h>

int main()

{

const float PI = 3.1416

float radius, circumference;

radius = 2.0;

circumference = 2.0 * PI * radius;

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit 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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