C Programming, Constants and Variables..

In this tutorial you will learn about Character Set, C Character-Set Table, Special Characters, White Space, Keywords and Identifiers, Constants, Integer Constants, Decimal Integers, Octal Integers, Hexadecimal integer, Real Constants, Single Character Constants, String Constants, Backslash Character Constants [Escape Sequences] and Variables.

Instructions in C language are formed using syntax and keywords. It is necessary to strictly follow C language Syntax rules. Any instructions that mis-matches with C language Syntax generates an error while compiling the program. All programs must confirm to rules pre-defined in C Language. Keywords as special words which are exclusively used by C language, each keyword has its own meaning and relevance hence, Keywords should not be used either as Variable or Constant names.

Character Set

The character set in C Language can be grouped into the following categories.

1. Letters
2. Digits
3. Special Characters
4. White Spaces

White Spaces are ignored by the compiler until they are a part of string constant. White Space may be used to separate words, but are strictly prohibited while using between characters of keywords or identifiers.

C Character-Set Table

Letters

Digits

Upper Case A to Z

0 to 9

Lower Case a to z

.

Special Characters

,

.Comma

&

.Ampersand

.

 .Period

^

.Caret

;

 .Semicolon

*

.Asterisk

:

.Colon

.Minus Sign

?

.Question Mark

+

.Plus Sign

.Aphostrophe

<

.Opening Angle (Less than sign)

.Quotation Marks

>

.Closing Angle (Greater than sign)

!

.Exclaimation Mark

(

.Left Parenthesis

|

.Vertical Bar

)

.Right Parenthesis

/

.Slash

[

.Left Bracket

\

.Backslash

]

.Right Bracket

~

.Tilde

{

.Left Brace

.Underscore

}

.Right Bracket

$

.Dollar Sign

#

.Number Sign

%

.Percentage Sign
.
.

.
.
.
White Space

1. Blank Space
2. Horizontal Tab
3. Carriage Return
4. New Line
5. Form Feed

Keywords and Identifiers

Every word in C language is a keyword or an identifier. Keywords in C language cannot be used as a variable name. They are specifically used by the compiler for its own purpose and they serve as building blocks of a c program.

The following are the Keyword set of C language.

.auto
.else
.register
.union

.break
.enum
.return
.unsigned

.case
.extern
.short
.void

.char
.float
.signed
.volatile

.const
.for
.size of
.while

.continue
.goto
.static
.

.default
.if
.struct
.

.do
.int
.switch
.

.double
.long
.typedef
.

some compilers may have additional keywords listed in C manual.

Identifiers refers to the name of user-defined variables, array and functions. A variable should be essentially a sequence of letters and or digits and the variable name should begin with a character.

Both uppercase and lowercase letters are permitted. The underscore character is also permitted in identifiers.

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3 Responses to C Programming, Constants and Variables..

  1. Darshan says:

    explain the use of in c programmin, xclusively in strings ????

  2. Darshan says:

    The use of !!

  3. nice one … thank you for sharing

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