Write pseudocode statements for: the declaration and initialisation of constants

11.1 Programming Basics – Declaration and Initialisation of Constants

Learning Objective

Write pseudocode statements for the declaration and initialisation of constants.

Key Concepts

• Constant: A named value that cannot be altered after it is set.
• Identifier: The name given to a constant; must follow the language’s naming rules.
• Initialisation: Assigning a value to a constant at the point of declaration.
• Scope: The region of the program where the constant can be accessed.

Pseudocode Syntax for Constants

In the Cambridge A‑Level pseudocode, a constant is declared with the CONST keyword followed by the identifier, an optional type, and the value it is to hold.

Examples in Context

1. Declare a constant for the number of days in a week:

   CONST DAYSINWEEK : INTEGER ← 7

2. Declare a constant for the tax rate used throughout a financial program:

   CONST TAX_RATE : REAL ← 0.20

3. Use a constant in an expression:

   To calculate the circumference of a circle, you might write:

   CONST PI : REAL ← 3.14159

   circumference ← 2 * PI * radius

   where the value of PI cannot be changed later in the program.

Mathematical Representation

The value of a constant can be shown mathematically, for example the constant π:

\$\pi = 3.14159\$

Suggested Diagram