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Access a public instance variable in the object

The last two statements in Listing 1 access a public instance variable belonging to the object. The first of the two statements assigns the stringvalue "Quit" to the variable. The second statement retrieves and displays that value.

Store a string value in the object's instance variable

Note the syntax of the first of these two statements. The value of the reference variable named obj is joined to the name of the object's public instance variable. (The name of the instance variable is text .) The assignment operator is used to store a string value in that instance variable.

You can think of this operation as involving the following steps:

  1. Get the object's reference from the variable named obj .
  2. Use that reference to locate the object in memory.
  3. Knock on the object's door and ask for access to the instance variable named text . (Access will be granted because the instance variable is declared public as you will see shortly.)
  4. Store the string value "Quit" in the instance variable using an assignment operator.

Get and display the value in the object's instance variable

The last statement does essentially the same thing in reverse.

  1. Get and use the object's reference to gain access to the object's public instance variable.
  2. Get the value stored in that instance variable.
  3. Concatenate that value to the literal string value "text".
  4. Pass the concatenated string to the WriteLine method of the static Console class to have it displayed on the standard output device (the black screen).

This produces the first line of output shown in Figure 1 .

Beginning of the class named TargetClass

The class definition for the class named TargetClass begins in Listing 2 .

Listing 2 . Beginning of the class named TargetClass.

public class TargetClass{public string text;

Declare a public instance variable

The code in the class begins by declaring a public instance variable. This is considered to be bad programming practice in most quarters unless the publicvariable is actually a constant, (which it is not).

This is the variable that is accessed by the last two statements in Listing 1 .

In most cases, instance variables should be declared private and should be made accessible through public accessor methods or public set and get methods. Youwill see examples of public access, set, and get methods later.

Different kinds of variables

I will generally refer to three kinds of variables:

  1. Instance variables - declared inside a class but outside of a method or constructor. (All variables in C# must be declaredinside a class. Unlike C++, there are no global variables or global functions in C#.)
  2. Local variables - declared inside a method or constructor.
  3. Class variable - declared inside a static class.

Any of these can be further qualified as follows:

  1. Reference variable - contains a reference to an object or contains null.
  2. Primitive variable - contains a value of a primitive type (int, float, double, etc.).

Instance variables

An instance variable belongs to a specific object. The lifetime of an instance variable is the same as the lifetime of the object to which it belongs.The scope of an instance variable depends on its access modifier such as public , private , or protected .

Questions & Answers

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 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
how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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