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In the last chapter, we explored how results are displayed and how numerical data are stored and processed using variables and assignment statements. In this chapter, we complete our introduction to the basics of C++ by presenting additional processing and input capabilities.

Assignment operators

Assignment operator (=) is used for assignment a value to a variable and for performing computations.

Assignment statement has the syntax:

variable = expression;

Expression is any combination of constants, variables, and function calls that can be evaluated to yield a result.


length = 25;

cMyCar = “Mercedes”;

sum = 3 + 7;

newtotal = 18.3*amount;

slope = (y2 – y1)/(x2 – x1);

The order of events when the computer executes an assignment statement is

- Evaluate the expression on the right hand side of the assignment operator.

- Store the resultant value of the expression in the variable on the left hand side of the assignment operator.


1. It’s important to note that the equal sign in C++ does not have the same meaning as an equal sign in mathematics.

2. Each time a new value is stored in a variable, the old one is overwritten.


// This program calculates the volume of a cylinder,

// given its radius and height


int main()


float radius, height, volume;

radius = 2.5;

height = 16.0;

volume = 3.1416 * radius * radius * height;

cout<<"The volume of the cylinder is "<<volume<<endl;

return 0;


The output of the above program:

The volume of the cylinder is 314.16

We can write multiple assignments , such as a = b = c = 25;. Because the assignment operator has a right-to-left associativity, the final evaluation proceeds in the sequence

c = 25;

b = 25;

c = 25;

Data type conversion across assignment operator

Note that data type conversion can take place across assignment operators, that is, the value of the expression on the right side of the assignment operator is converted to the data type of the variable to the left side of the assignment operator.

For example, if temp is an integer variable, the assignment temp = 25.89 causes the integer value 25 to be stored in the integer variable temp.

Assignment variations

C++ also use a shorthand notation to perform an operation and an assignment at the same time. This is denoted by an operator followed by an equal sign. For example, to add 4 to the variable x and assign x to the result, you say: x += 4. Figure 1 illustrates assignment operator and all assignment variations.

Variations of assignment

Assignment statements such as sum += 10 or its equivalent, sum = sum + 10, are very common in C++ programming.

Increment and decrement operators

For the special case in which a variable is either increased or decreased by 1, C++ provides two unary operators: increment operator and decrement operator .

Increment operator and decrement operator

The increment (++) and decrement (--) unary operators can be used as prefix or postfix operators to increase or decrease value.

A prefix operator is placed before a variable and returns the value of the operand after the operation is performed.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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
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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