WHAT IS C TOKENS AND VARIABLE OF C TOKENS IN DETAILS

 WHAT IS TOKEN?

 

In a passage of that individual words and punctuation marks are called tokens similarly in ac program the smallest

Individuals units are known as c tokens. 

C Tokens have six types of tokens. 

C tokens Variable....

1.  Keywords                                                                                       
2.  Identifier                                                                                  
3.  Constant 
4.   String
5. Operations
6.  Special symbolic

Keywords

Every c word is classified as either keywords or an identifier all keywords have fixed meanings and these meaning cannot be changed building for program statements there are 32 words defined as keywords these have predefined user and cannot be used for any other purpose in c program they are always written in lowercase letter the list of these keywords in given In table.

Auto	Double	Int	Struct
Break	Else	Long	Switch
Case	Enum	Register	Typeof
Char	Extern	Return	Union
Const	Float	Short	Unsigned
Continue	For	Signed	Void
default	goto	Size of	Volatile
Do	It	Static	while

Identifier

Identifier refers to the name of variable. Functions and arrays. These

Are users defined names and consist of a sequence of letters and digits with letter as a first character both lowercase and uppercase are permitted

Constants

Constant In C refer to fixed value that do not changes during the executing after program .C supports several type of constants illustrated .

                                    Type of Constants

1)  Numeric constant

• Integer constant

• Real constant

2)  Character constant

•  Single character constant
  

•  String character constant

Integer constant :-

Refers to a sequence of digits. 

There are three types of integers, namely, decimal, integer, octal, integer consist of a set of digits 0 to 7.

Hexadecimal integer consist of a set of digits 0 to 15.

Real constant:  

represented by numbers containing fractional parts.

Single constant :

contains a single character enclosed within A PAIR of single quote mark e.g. ‘X’.

String constant : 

is a sequence of character enclosed in double quotes e.g. “hello”.

Variable

A variable is a data name that may be used to store and holding data a value a variable may take different values at different times during execution

Rules for declare any variable name

• They must begin with a letter.

•  ANSI standards recognizes a length of 31 characters however length should not be normally more than eight characters.

•  Uppercase and lowercase are significant, that is variable total is not same as total or TOTAL.

•  It should not be a keyword
•  White spaces is not allowed