C Tokens and Character set in C

1. keywords
2. Identifiers
3. Constants
4. String
5. Special Character
6. Operators

Keywords

• In C keyword has a special meaning. It is special word of C which has predefined meaning .
• there are 32 set of keywords in C Language
• they are displayed by white colour in  turbo C 

Identifiers

• It refer to the name of the variable ,function and array. they are user defined name ,consists of sequence of letter's , digits ,and upper case , lower case both type letters are allowed here .

Rules for Identifiers

1 First character must be an alphabet

2 Must contain only letters , digits or underscore

3 Only first 31 character are significant

4 Cannot use a key word

5 must not contain white space  

C constants

• Constants means one whose value is not going to changed during the execution of whole program.
• they are generally known as global declared variable

Strings

• String is a sequence of character that is treated as single data item. When group of character is written in double quotation it is considered as string.
• string can not be scan directly array of string has to be declared.

Operators

• Operator is a symbol that tells the compiler to perform the specific tasks.
• they decide the priority of the operation to be performed .
• There are eight type of operators in C language 

The character in C are categories in four type

1 letters

2 digits

3 special characters

4 white space

Compiler do not consider white space till they are not used in string constant