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Instead, you can think about the compartments and refer to them in terms of their names. (Names are easier for most people to remember and understand than numeric addresses.) Keep in mind, however, that computer memory locations don't really have names. Deep inside the computer program, the namesthat you use to identify compartments in memory are cross-referenced to memory addresses. At the lowest level, the program works with memory addresses insteadof names.

Execute an algorithm

A computer program always executes some sort of procedure or algorithm. The algorithm may be very simple (such as how to make a peanut butter sandwich) , or it may be very complex as would be the case for a spreadsheet program. As theprogram executes the algorithm, it uses the random access memory to store and retrieve the data that is needed to execute the algorithm.

Declaring a variable

In Scratch, it is necessary to establish the name of a variable before you can use it. (That is not the case in some programming languages such as Python and JavaScript.)

In programmer jargon, this is referred to as declaring a variable . The process of declaring a variable causes memory to be set aside to contain avalue, and causes that chunk of memory to be given a name. That name can be used later to refer to the value stored in that chunk of memory.

Some programming languages, (not including Scratch), require that the variable declaration also specify the type of data that will be storedin a variable.

Case sensitivity

The name of a variable is case sensitive in Scratch (but the name may not be case sensitive in other programming languages) . In other words, the name aVariable is not the same as the name avariable in case-sensitive programming languages. If both names were used in the sameprogram, they would refer to two different variables.

Use names to access values

Variables typically have names like price , cost , and markup . The names of the variables give us easy access to the values stored in the variables.

Some operations cause the value of a variable to change while other operations simply access the value without changing it.

Storing and retrieving

As the program executes, the values stored in variables can be replaced by other values. In that way, the values of the variables can change asthe program executes. (In other words, the value of a variable can vary over time.)

It is also possible to retrieve the value stored in a variable without modifying it. In that way, the values of variables can be used to evaluateexpressions without modifying those values.


Where does data originate ?

The data used by a computer program can originate from a variety of sources. For example, it can be entered from the keyboard. It can be read from a diskfile. It can be downloaded from a web site, etc.

Hard coded data

The data values can also be coded into the program when the program is written. In this case, we would call it a literal or a literal value .

A value coded into the program

That is just about all there is to understanding literals. There are some special rules that come into play in certain situations, and I will discussthose rules at the appropriate points in time. For now, just remember that a literal is a value that is coded into the program when the program is written.

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, Teaching beginners to code. OpenStax CNX. May 27, 2013 Download for free at http://cnx.org/content/col11498/1.20
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