Identifiers and Data Types

Variable

• Name given to a distinct memory location and contains a value
• Can be updated throughout the program

Constant

• Name given to a distinct memory location and contains a value
• Cannot be updated once it is created
• Python does not have true constants. Instead, use variables written in all uppercase to show that they should be treated as constants.

Data Types

• INTEGER: Represents a whole number
• REAL: Represents a floating point number
• CHAR: Represents a character, surrounded by single quotes (‘A’)
• STRING: Sequence of characters, surrounded by “double quotes”
• BOOLEAN: The logical values True or False
• ARRAY: A list of same data type
• FILE: Resource for recording data in a computer
• NULL: No Value

No output yet.

Identifier

• Name given to an entity distinctly identifying an entity in a program
• Variable names, function names, class names all are identifiers
• It’s a good practice to use PascalCase or camelCase
• Rules
  • Must be unique
  • Cannot have spaces
  • Must begin with a letter
  • Can consist of letters, digit or underscore
  • Reserved words in the language cannot be used (eg. return, int, float, if)
  • Names are case sensitive