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Numeric constants of C are usually just the written version of numbers. For example 1, 0, 56.78, 12.3e-4. We can specify our constant in octal or hexadecimal, or force them to be treated as long integers.

  • Octal constants are written with a leading zero : -0.15
  • Hexadecimal constants are written with a leading 0x : 0x1ae
  • Long constants are written with a trailing L : 890L or 890l

Character constants are usually just the character enclosed in single quotes; ‘a’, ‘b’, ‘c’. Some characters can’t be represented in this way, so we use a 2 character sequence (escape sequence).

‘\n’ newline
‘\t’ horizontal tab
‘\v’ vertical tab
‘\b’ backspace
‘\r’ carriage return
‘\\’ backslash
‘\’’ single quote
‘\”’ double quotes
‘\0’ null (used automatically to terminate character strings)

Character constants participate in numeric operations just as any other integers (they are represented by their order in the ASCII character set), although they are most often used in comparison with other characters.

Character constants are rarely used, since string constants are more convenient. A string constant is a sequence of characters surrounded by double quotes e.g. “Brian and Dennis”.

A character is a different type to a single character string. This is important.

It is helpful to assign a descriptive name to a value that does not change later in the program. That is the value associated with the name is constant rather than variable, and thus such a name is referred to as symbolic constant or simply a constant.


Variables are the names that refer to sections of memory into which data can be stored.

Let’s imagine that memory is a series of different size boxes. The box size is memory storage area required in bytes.In order to use a box to store data, the box must be given a name, this process is known as declaration . It helps if you give a box a meaningful name that relates to the type of information and it is easier to find the data.The boxes must be of the correct size for the data type you are going to put into it. An integer number such as 2 requires a smaller box than a floating point number as 123e12.

Data is placed into a box by assigning the data to the box. By using the name of the box you can retrieve the box contents, some kind of data.

Variable named by an identifier. The conventions of identifiers were shown in 1.3.3.

Names should be meaningful or descriptive, for example, studentAge or student_age is more meaningful than age, and much more meaniful than a single letter such as a.


Programming languages have a set of operators that perform arithmetical operations , and others such as Boolean operations on truth values, and string operators manipulating strings of text. Computers are mathematical devices , but compilers and interpreters require a full syntactic theory of all operation in order to parse formulae involving any combination correctly.


An expression in a programming language is a combination of values, functions, etc. interpreted according to the particular rules of precedence and association for a particular programming language, which computes and returns another value.

Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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?
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Introduction to computer science. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10776/1.1
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