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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

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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