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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

how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
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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