Pseudocode:
Selection & Iteration

IF / ELSE · CASE OF · FOR · WHILE · REPEAT UNTIL

CSZoneCambridge IGCSE Computer Science 0478

Selection — IF Statements

Conditional Branching

IF score >= 70
THEN
OUTPUT "Pass"
ELSE
OUTPUT "Fail"
ENDIF

// Nested IF
IF score >= 90
THEN OUTPUT "A"
ELSE IF score >= 70
THEN OUTPUT "B"
ELSE OUTPUT "C"
ENDIF
ENDIF

All IF statements must end with ENDIF in Cambridge 0478 pseudocode

CASE OF Statement

Multiple Choice Selection

CASE OF grade
'A' : OUTPUT "Excellent"
'B' : OUTPUT "Good"
'C' : OUTPUT "Pass"
OTHERWISE : OUTPUT "Fail"
ENDCASE

CASE OF is used when selecting from several fixed options — cleaner than many nested IFs

OTHERWISE handles any value not covered by the listed cases (like ELSE)

Iteration — Loops

FOR, WHILE, REPEAT UNTIL

// FOR — known number of repeats
FOR counter ← 1 TO 10
OUTPUT counter
NEXT counter

// WHILE — condition checked before
WHILE answer <> "yes" DO
INPUT answer
ENDWHILE

// REPEAT UNTIL — condition checked after
REPEAT
INPUT number
UNTIL number > 0

Exam Practice

Have a go at this question

Cambridge IGCSE 0478 style

Write pseudocode using a WHILE loop to keep asking the user for a password until they enter the correct one ("Secret99"). Output "Access Granted" when correct.

4 marks

INPUT password
WHILE password <> "Secret99" DO
OUTPUT "Incorrect. Try again."
INPUT password
ENDWHILE
OUTPUT "Access Granted"

Key Takeaways

What to Remember

IF...THEN...ELSE...ENDIF — condition-based branching; must always close with ENDIF

CASE OF...ENDCASE — multiple fixed options; OTHERWISE handles remaining cases

FOR...NEXT: fixed count; WHILE...ENDWHILE: condition checked before; REPEAT...UNTIL: checked after

REPEAT UNTIL always runs at least once; WHILE may never run if condition is false from the start