8.1 Programming

Storing Data

Programs need to store data in memory locations. We categorize these into two types:

• Variables: The value can change during the program execution (e.g., a Score).
• Constants: The value remains fixed throughout (e.g., PI = 3.142).

IGCSE Data Types:

• INTEGER: Whole numbers (e.g., 10, -5).
• REAL: Numbers with decimals (e.g., 15.5).
• CHAR: A single character (e.g., "A").
• STRING: Multiple characters (e.g., "Hello").
• BOOLEAN: TRUE or FALSE.

Sequence and Selection

All programs are built using three main structures. The first two are:

• Sequence: Statements are executed one after another in order.
• Selection: The program takes different paths based on a condition (e.g., IF...THEN...ELSE or CASE).

Repeating Code

Cambridge focuses on three types of loops in pseudocode:

1. FOR...TO...NEXT: Count-controlled (runs a set number of times).
2. WHILE...DO...ENDWHILE: Pre-condition (checks the condition before running).
3. REPEAT...UNTIL: Post-condition (runs at least once, checks after).