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

Prefix and postfix operators have different effects when used in a statement

b = ++a;

will first increase the value of a to 6, and then assign that new value to b. It is equivalent to

a = a +1;

b = a;

On the other hand, execution of the statement

b = a++;

will first assign the value of 5 to b, and then increase the value of a to 6. It is now equivalent to

b = a;

a = a + 1;

The decrement operators are used in a similar way.

Example

// Preincrementing and postincrementing

#include<iostream.h>

int main()

{

int c;

c = 5;

cout<<c<<endl; // print 5

cout<<c++<<endl; // print 5 then postincrement

cout<<c<<endl<<endl; // print 6

c = 5;

cout<<c<<endl; // print 5

cout<<++c<<endl; // preincrement then print 6

cout<<c<<endl; // print 6

return 0; // successful termination

}

The output of the above program:

5

5

6

5

6

6

Formatting number for program output

Besides displaying correct results, a program should present its results attractively with good formats.

Stream manipulators

Stream manipulator functions are special stream functions that change certain characteristics of the input and output.

The main advantage of using manipulator functions is they facilitate the formatting of the input and output streams.

- setw(): The setw() stands for set width. This manipulator is used to specify the minimum number of the character positions on the output field a variable will consume.

- setprecision(): The setprecision() is used to control the number of digits of an output stream display of a floating point value. Setprecision(2) means 2 digits of precision to the right of the decimal point.

To carry out the operations of these manipulators in a user program, you must include the header file<iomanip.h>.

Example

#include<iostream.h>

#include<iomanip.h>

int main()

{

cout<<setw(3)<<6<<endl

<<setw(3)<<18<<endl

<<setw(3)<<124<<endl

<<"---\n"

<<(6+18+124)<<endl;

return 0;

}

The output of the above program:

Output of above program

Example:

cout<<“|”<<setw(10)

<<setioflags(ios::fixed)<<setprecision(3)<<25.67<<”|”;

causes the printout

Output of above code segment

- setiosflags: This manipulator is used to control different input and output settings.

setioflag(ios::fixed) means the output field will use conventional fixed-point decimal notation.

setiosflag(ios::showpoint) means the output field will show the decimal point for floating point number.

setiosflag(ios::scientific) means the output field will use exponential notation.

Note: In the absence of the ios::fixed flag, a floating point number is displayed with a default of 6 significant digits. If the integral part of the number requires more than 6 digits, the display will be in exponential notation.

Below are some other format flags for use with setiosflags().

Flags for use with setiosflags()

Example

// This program will illustrate output conversions

#include<iostream.h>

#include<iomanip.h>

int main()

{

cout<<"The decimal (base 10) value of 15 is "<<15<<endl

<<"The octal (base 8) value of 15 is "

Questions & Answers

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 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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket 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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