2.3 Python Tokens (BT101CO)

Keywords are reserved words that have a fixed, predefined meaning for the Python interpreter. They cannot be used as names for variables, functions, or any other identifiers.

• Examples: if, else, while, for, break, import, def, return, True, False.
• Note: Python keywords are case-sensitive.

Identifiers are names given to various program elements, such as variables, functions, classes, and objects. The book outlines specific rules for naming identifiers:

• Must begin with a letter (A-Z, a-z) or an underscore (_).
• Can be followed by any number of letters, digits (0-9), or underscores.
• Cannot be a keyword.
• Special symbols (except underscore) like @, $, and % are not allowed.
• Examples: student_name, total_sum, _temp.

Literals represent fixed data values in a program. The Kamthanes categorize them by the type of data they hold:

• String Literals: Text enclosed in quotes (e.g., "Ashok", 'Python').
• Numeric Literals: Whole numbers or decimals (e.g., 100, 3.14).
• Boolean Literals: True and False.
• Special Literal: None, used to indicate the absence of a value.

Operators are special symbols used to perform computations on data (operands). The textbook focuses on several categories:

• Arithmetic Operators: +, -, *, /, % (modulus), ** (exponent), // (floor division).
• Relational Operators: ==, !=, <, >, <=, >=.
• Logical Operators: and, or, not.
• Assignment Operators: =, +=, -=, etc.

Punctuators are symbols used to organize the code structure and indicate the boundaries of expressions or blocks.

• Common Punctuators: ( ), [ ], { }, @, ,, :, ., =, ;.
• For example, the colon (:) is used at the end of if or for headers to signify the start of an indented block.