What is Pseudocode?

What is Pseudocode?

Pseudocode is a way of writing out the steps of an algorithm using simple English-like instructions. It is not a real programming language — you cannot run it on a computer. It is designed to be easy for humans to read and understand.

Think of it like a recipe. A recipe tells you the steps to make a meal in plain language. Pseudocode tells you the steps to solve a problem in plain language. The computer does not need to understand it — the programmer does.

Why Does Cambridge Have Its Own Style?

This is the part most students miss. Cambridge IGCSE Computer Science (0478) uses a specific pseudocode style defined in the syllabus. If you write pseudocode in a different style — even if your logic is completely correct — you may lose marks.

Cambridge uses its own style so that every student and every examiner is reading the same language. There is no confusion about what a keyword means.

Cambridge Pseudocode Keywords You Must Know

Input and Output

Use INPUT to receive data from the user. Use OUTPUT to display data. Some mark schemes also accept PRINT — but OUTPUT is the safest choice.

Variables and Assignment

Use the left arrow ← to assign a value to a variable. Do not use = like in Python. This is one of the most common mistakes in the exam.

IF Statements

Always close your IF statement with ENDIF. Cambridge is strict about this. Every block must be opened and closed correctly.

FOR Loops

Use FOR … TO … NEXT when you know exactly how many times the loop will run. Always include the variable name after NEXT.

WHILE Loops

Use WHILE … ENDWHILE when you do not know how many times the loop will run. The condition is checked at the start — so if the condition is already false, the loop never runs.

REPEAT UNTIL Loops

Use REPEAT … UNTIL when the loop must run at least once. The condition is checked at the end — the loop always runs a minimum of one time.

A Complete Pseudocode Example

Here is a complete example using INPUT, OUTPUT, a FOR loop and an IF statement together. This is the kind of question you will see in your exam:

Notice how every block is closed — ENDIF closes the IF, NEXT closes the FOR. This structure is what Cambridge examiners look for.

Common Pseudocode Mistakes in the Exam

These are the mistakes that cost students marks every single year:

• Using = instead of ← for assignment. Always use the arrow.
• Forgetting ENDIF or ENDWHILE. Every block must be closed.
• Writing pseudocode like Python. No colons, no indentation rules — Cambridge has its own style.
• Using print() instead of OUTPUT. OUTPUT is the Cambridge keyword.
• Not using the variable names from the question. If the question gives you variable names, use them exactly.
• Mixing up WHILE and REPEAT. WHILE checks at the start. REPEAT checks at the end.

How to Practise Pseudocode for IGCSE

The best way to get confident with pseudocode is simple: do it by hand, on paper, without looking at notes.

1. Read a problem — for example "write pseudocode to input 10 numbers and output the largest."
2. Write your pseudocode on paper without any help.
3. Check it against the Cambridge mark scheme.
4. Identify exactly where you went wrong.
5. Repeat the next day.

Summary — What You Need to Remember

• Pseudocode is plain English instructions for an algorithm — not a real programming language
• Cambridge IGCSE uses its own specific pseudocode style — learn it, use it
• Key keywords: INPUT, OUTPUT, ←, IF/THEN/ELSE/ENDIF, FOR/NEXT, WHILE/ENDWHILE, REPEAT/UNTIL
• Always close every block — ENDIF, ENDWHILE, NEXT
• Practise on paper, check against mark schemes, repeat daily