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Character Set and Tokens in Python

 Character Set: Character Set in Python consist of  valid characters such as alphabets, digits or special characters that are recognized by the library of Python Language.

Alphabets:                    A,B,......Y,Z or a,b,.......y,z.

Digits:                         0,1,2,3,4,5,6,7,8,9

Special Character:     ~!@#$%^&*()_+{}[];:'"\,./<> etc.

White spaces   :          Blank space, new line, etc.

Token: The smallest individual unit in a program is referred as 'Token'. It is also called Lexical Element or Lexical Unit.

It can be categorized as:

1. Keywords: Keywords are the reserved words that has specific function in a program. These words are used while writing program to get desired output. The keywords are executed  as its purpose/action is already explained inside the language interpreter.

  • All Keywords are written in lower case.
  • Keywords are also called 'Reserved Words'.
  • There are 33 keywords in Python.

2. Identifiers: Identifiers are the fundamental building blocks of a program that are used to identify names of different elements of the program such as variable.

Guidelines for Creating Identifiers in Python:

  • An identifier is an arbitrary sequence of letters in lower case(a-z) & upper case(A-Z), digits(0-9) and underscore(_).
  • The First Character of the identifier must be a letter or underscore. It must not be start with digits(0-9).
  • An identifier must not be a 'keyword'.
  • An identifier must not contain any special character except underscore.

3.Puntuators: Puntuators are used as marks or as separators in a program. The characters used as puntuators are ' " # \ etc.

4. Literals: Literals are data items that never change their value during the execution of a program. These are commonly called constant. 

In Python there are four types of literals(constants):

  • Integer Literals: Integer literals are whole numbers without any fractional part. It may be positive or negative. ex- 2,5,1324,-145 etc.

  • Character Literals: Character literals refer to single character that is enclosed in a single quote. For example: 'A' ,'1' etc.
  • Floating Literals: Floating literals are fractional number. They may be positive or negative. Ex:12.234, -9.256 etc. 
  • String Literals: A string literal is a sequence of characters enclosed within pair of single or double quotes. Ex: 'AMIT', "Hello" etc.

5. Operator: Operators are tokens that does computation with designated or given values in an expression. Operators applied on operands form an expression.

Operand is the value or variable on which calculation is performed.

*Keep Learning * In Next Note I will Explain Operator*TQ

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