Question

C Programming Tokens, Variables, Data Types, Keywords, Identifiers, Constants

Answer 1

Character set

A character set is a set of alphabets, letters and some special characters that are valid in C language.

Token

A token is the smallest unit in a 'C' program. A token is divided into six different types as follows,

1. Keywords               (eg: int, while),
2. Identifiers               (eg: main, total),
3. Constants              (eg: 10, 20),
4. Strings                    (eg: “total”, “hello”),
5. Special symbols  (eg: (), {}),
6. Operators              (eg: +, /,-,*)

Variables

It is a data name used for storing a data value. Its value may be changed during the program execution. The value of variables keeps on changing during the execution of a program. 

Data Types

A data type specifies the type of data that a variable can store such as integer, floating, character, etc.

Keywords

 A keyword is a reserved word. You cannot use it as a variable name, constant name, etc. There are only 32 reserved words (keywords) in the C language.

Auto	Double	Int	Struct
Break	Else	Long	Switch
Case	Enum	Register	Typedef
Char	Extern	Return	Union
Const	Float	Short	Unsigned
Continue	For	Signed	Void
Default	Goto	Sizeof	Volatile
Do	If	Static	while

Identifiers

Identifiers are names of variables, functions, and arrays. They are user-defined names, consisting sequence of letters and digits, with the letter as the first character. 

Constants

Values do not change during the execution of the program Types:

Numerical constants:

Integer constants

These are the sequence of numbers from 0 to 9 without decimal points or fractional part or any other symbols. It requires minimum two bytes and maximum four bytes.

Eg: 10,20, + 30, – 14

Real constants

It is also known as floating point constants. Eg: 3.5, 6.342

Character constants:

Single character constants

A character constant is a single character. Characters are also represented with a single digit or a single special symbol or white space enclosed within a pair of single quote marks

Eg: ‘a’, ‘6’, “ ”.

String constants

String constants are sequence of characters enclosed within double quote marks. Eg: “Hello”, “goeduhub”, “234”