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Postfix increment and decrement operators

The program shown in Listing 1 illustrates the use of the increment (++) and decrement (--) operators in their postfix form.

Behavior of increment operator

Given a variable named x , the two statements shown in Figure 1 are equivalent.

Figure 1 . Behavior of increment operator.
x++; x = x + 1;

Behavior of decrement operator

The two statements shown in Figure 2 are equivalent.

Figure 2 . Behavior of decrement operator.
x--; x = x - 1;

And the answer to question is...

D. 6 4 9.3 7.300000000000001

Inaccurate results

Regarding the program output, you will note that there is some arithmetic inaccuracy when this program is executed using JDK 1.6. Ideally, the outputvalue 7.300000000000001 should simply be 7.3 without the very small additional fractional part, but that sort of thing often happens when using floating types.

What isn't clear

What isn't clear is whether the increment and decrement operators will be used in the adjustment or update clause of a for loop as shown in Listing 2 .

Listing 2 . Adjustment clause of a for loop.
public class Increment02{ public static void main(String args[]){ new Worker().doWork();}//end main() }//end class definitionclass Worker{ public void doWork(){for(int cnt = 0;cnt<5;cnt++){ System.out.println(cnt);}//end for loop }//end doWork()}//end class definition

One could argue that the adjustment clause, which reads cnt++ in Listing 2 , is an independent expression contained in a larger overall construction. If so, the use of the increment operator would notbe excluded by the specification .

In any event, the increment operator behaves as described in Figure 1 even when used in this way. The safest thing would be for you to assume that it will be used in thisway and to be prepared for it on the exam.

What the student apparently doesn't need to know

Prefix and postfix forms are both available

The increment and decrement operators have both a prefix form and a postfix form.

Can be fairly complex

It is possible to construct some fairly complex scenarios when using these operators in both the prefix and postfix forms and combining them into expressions.

Postfix only on the exam

However, according to the specification , only the postfix form is used on the AP exam. Also, according to the specification , the increment and decrement operators are not included in other expressions on the AP exam.

Another program

Under the philosophy that it is always good to learn a little more about a topic than is absolutely required before taking an exam on that topic, I will present and explain a programthat illustrates the use of prefix and postfix increment operators both outside and included inside of another expression.

What output is produced by the program shown in Listing 3 ?

  • A. 5 50 500 501 5001 5001
  • B. 6 51 501 501 5000 5001
  • C. 6 51 500 501 5001 5001
  • D. 6 50 500 501 5001 5001
Listing 3 . More complex increment program.
public class Increment03{ public static void main(String args[]){ new Worker().doWork();}//end main() }//end class definitionclass Worker{ public void doWork(){int w = 5; int x = 50;int y = 500; int z = 5000;++w;//prefix incrementx++;//postfix increment System.out.println(w + " " +x + " " + y++ + " " +y + " " + ++z + " " +z); }//end doWork()}//end class definition

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
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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.
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Damian Reply
absolutely yes
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it is a goid question and i want to know the answer as well
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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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