StudyDeck
Dashboard

Variables & Constants

Exam code: 2210
Written by: Ashika|Reviewed by: Caroline Carroll|Updated 2 July 2026

Variables & Constants

Variables & Constants

What is a variable?

  • A variable is an identifier that can change in the lifetime of a program

  • Identifiers should be:

    • In mixed case (Pascal case)

    • Only contain letters (A-Z, a-z)

    • Only contain digits (0-9)

    • Start with a capital letter and not a digit

  • A variable can be associated a datatype when it is declared

  • When a variable is declared, memory is allocated based on the data type indicated

Pseudocode

DECLARE <identifier> : <datatype>

DECLARE Age : INTEGER

DECLARE Price : REAL

DECLARE GameOver : BOOLEAN

Python

score = int() # whole number

cost = float() # decimal number

light = bool() # data can only have one or two values

What is a constant?

  • A constant is an identifier set once in the lifetime of a program

  • Constants are generally named in all uppercase characters

  • Constants aid the readability and maintainability

  • If a constant needs to be changed, it should only need to be altered in one place in the whole program

Pseudocode

CONSTANT <identifier> ← <value>

CONSTANT PI ← 3.142

CONSTANT PASSWORD ← "letmein"

CONSTANT HIGHSCORE ← 9999

Python

PI = 3.142

VAT = 0.20

PASSWORD = "letmein"

Was this revision note helpful?

Build on this topic

Check your understandingTry an Exam Question on this topic
Test your recallReinforce key facts and definitions with Flashcards
Variables & Constants · Revision Notes · Computer Science · StudyDeck