Character Set :
A character refers to the digit, alphabet or special symbol used
to data represetation.
1. Alphabets
:
A-Z, a-z
2. Digits
:
0-9
3. Special
Characters : ~ ! @ # $ % ^ & * ( ) _ + { } [ ] -
< > , . / ? \ | : ; " '
4. White
Spaces :
Horizontal
tab, Carriage return, New line, form feed
Identifier :
Identifier is the name of a variable that is made up from
combination of alphabets, digits and underscore.
Variable :
It is a data name which is used to store data and may change
during program execution. It is opposite to constant. Variable name is a name
given to memory cells location of a computer where data is stored.
* Rules for variables:
·
First character should be letter or alphabet.
·
Keywords are not allowed to use as a variable name.
·
White space is not allowed.
·
C is case sensitive i.e. UPPER and lower case are significant.
·
Only underscore, special symbol is allowed between two
characters.
·
The length of indentifier may be upto 31 characters but only only
the first 8 characters are significant by compiler.
·
(Note: Some compilers allow variable names whose length may be
upto 247 characters. But, it is recommended to use maximum 31 characters in
variable name. Large variable name leads to occur errors.)
Keywords :
Keywords are the system defined identifiers.
All keywords have fixed meanings that do not change.
White spaces are not allowed in keywords.
Keyword may not be used as an indentifier.
It is strongly recommended that keywords should be in lower case letters.
All keywords have fixed meanings that do not change.
White spaces are not allowed in keywords.
Keyword may not be used as an indentifier.
It is strongly recommended that keywords should be in lower case letters.
There are totally 32(Thirty Two)
keywords used in a C programming.
int
|
float
|
double
|
long
|
short
|
signed
|
unsigned
|
const
|
if
|
else
|
switch
|
break
|
default
|
do
|
while
|
for
|
register
|
extern
|
static
|
struct
|
typedef
|
enum
|
return
|
sizeof
|
goto
|
union
|
auto
|
case
|
void
|
char
|
continue
|
volatile
|
Escape Sequence
Characters (Backslash Character Constants) in C:
C supports some special escape sequence characters that are used
to do special tasks.
These are also called as 'Backslash characters'.
Some of the escape sequence characters are as follow:
Character Constant
|
Meaning
|
\n
|
New line (Line break)
|
\b
|
Backspace
|
\t
|
Horizontal Tab
|
\f
|
Form feed
|
\a
|
Alert (alerts a bell)
|
\r
|
Carriage Return
|
\v
|
Vertical Tab
|
\?
|
Question Mark
|
\'
|
Single Quote
|
\''
|
Double Quote
|
\\
|
Backslash
|
\0
|
Null
|
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