Indentation and comments in pseudocode

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. Which symbol starts a comment in Cambridge pseudocode?

A //

B #

2. How far are the statements inside a FOR loop indented?

A Not indented, lined up with FOR

B Four spaces in from the FOR line

3. Where should ELSE be placed in an IF statement?

A Lined up with its IF

B Indented four spaces under the IF

4. Which is a correct comment on its own line?

A / Ask the user for a mark

B // Ask the user for a mark

5. Which line has a correct comment after a statement?

A Count <- Count + 1 // add one to count

B // Count <- Count + 1 add one to count

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1// Add the mark to the total		AThe loop body is not indented. OUTPUT Count should be indented four spaces so it is clearly inside the loop.
2Total <- Total + Mark // running total		BA comment on its own line. The computer ignores it; it explains the code to a human reader.
3The body of a FOR loop is indented four spaces so the repeated statements stand out		CELSE is indented. It should line up with its IF at the left edge.
4ELSE lines up with its IF, and the statements in each branch are indented four spaces		DFOR Count <- 1 TO 5 OUTPUT Count NEXT Count
5FOR Count <- 1 TO 3 OUTPUT Count NEXT Count		EIF Mark >= 50 THEN OUTPUT "Pass" ELSE OUTPUT "Fail" ENDIF
6IF Age >= 16 THEN OUTPUT "Adult" ELSE OUTPUT "Child" ENDIF		FA comment after a statement. The assignment still runs and everything after // is ignored.

Definitions

Fill in the Blanks

Complete each line of code by filling in the missing parts.

__ Ask the user for a name INPUT Name

FOR Count <- 1 TO 5 OUTPUT Count __ show the number NEXT Count

IF Mark >= 50 THEN ____OUTPUT "Pass" ENDIF

WHILE Num > 0 DO Num <- Num - 1 ________

FOR Count <- 1 TO 3 __ Print the count OUTPUT Count

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A total <- 0

B FOR i <- 1 TO 5

C INPUT n

D total <- total + n # add

E NEXT i

Question 2

A WHILE n > 0 DO

B /* count down by one */

C n <- n - 1

D ENDWHILE

Question 3

A IF age >= 16 THEN

B OUTPUT "Adult"

C ELSE THEN

D OUTPUT "Child"

E ENDIF

Question 4

A REM Add up five marks

B total <- 0

C FOR i <- 1 TO 5

D total <- total + i

E NEXT i

Question 5

A IF score > 50 THEN

B / score is a pass

C OUTPUT "Pass"

D ENDIF

Answer Key

Indentation and comments in pseudocode

Section A: Quick Questions

A — //

B — Four spaces in from the FOR line

A — Lined up with its IF

B — // Ask the user for a mark

A — Count <- Count + 1 // add one to count

Section B: Match the Pairs

// Add the mark to the total → A comment on its own line. The computer ignores it; it explains the code to a human reader.

Total <- Total + Mark // running total → A comment after a statement. The assignment still runs and everything after // is ignored.

The body of a FOR loop is indented four spaces so the repeated statements stand out → FOR Count <- 1 TO 5 OUTPUT Count NEXT Count

ELSE lines up with its IF, and the statements in each branch are indented four spaces → IF Mark >= 50 THEN OUTPUT "Pass" ELSE OUTPUT "Fail" ENDIF

FOR Count <- 1 TO 3 OUTPUT Count NEXT Count → The loop body is not indented. OUTPUT Count should be indented four spaces so it is clearly inside the loop.

IF Age >= 16 THEN OUTPUT "Adult" ELSE OUTPUT "Child" ENDIF → ELSE is indented. It should line up with its IF at the left edge.

Section C: Definitions

// — Starts a comment in Cambridge pseudocode. Statements inside a loop or IF are indented four spaces, and ELSE lines up with its IF, so the structure is easy to read.

Section D: Fill in the Blanks

// Ask the user for a name
INPUT Name

FOR Count <- 1 TO 5
    OUTPUT Count // show the number
NEXT Count

IF Mark >= 50 THEN
    OUTPUT "Pass"
ENDIF

WHILE Num > 0 DO
    Num <- Num - 1
ENDWHILE

FOR Count <- 1 TO 3
    // Print the count
    OUTPUT Count

Section E: Spot the Error

D — A comment after a statement starts with //, not #. The line should be ' total <- total + n // add'.

B — Cambridge pseudocode comments start with //. The /* ... */ style belongs to other languages. The line should be ' // count down by one'.

C — ELSE stands on its own line, lined up with its IF. Only IF takes THEN. The line should be 'ELSE'.

A — Cambridge pseudocode starts a comment with //, not REM. The line should be '// Add up five marks'.

B — A comment needs two slashes, //. A single / would be read as code. The line should be ' // score is a pass'.