Relational operators

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Quick Questions

Shade in the A or B circle for each question.

1. What type of value does the expression Score > 50 give?

A BOOLEAN (TRUE or FALSE)

B INTEGER (a number)

2. Which operator means 'not equal to' in IGCSE pseudocode?

A <>

B !=

3. Age is 16. What does Age >= 16 give?

A FALSE

B TRUE

4. Age is 16. What does Age > 16 give?

A TRUE

B FALSE

5. A pass mark is 40 or more. Which condition is correct?

A Mark >= 40

B Mark > 40

Match the Pairs

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

Left column		Right column
1Age <> 18		AThe boundary is wrong. A person aged exactly 18 should be allowed, so the test should be Age >= 18 and not Age < 18.
2Score >= 50		BMark < 40
3Check that Mark is below 40 only, so a Mark of exactly 40 gives FALSE		CTRUE when Age is not equal to 18, otherwise FALSE
4Check whether Password is exactly the same as the stored value Secret		DTRUE when Score is 50 or more, so 50 itself gives TRUE
5IF Age != 18 THEN		E!= is not a pseudocode operator. 'Not equal to' is written <>, so it should be IF Age <> 18 THEN.
6IF Age < 18 THEN // must be 18 or over to vote		FPassword = Secret

Definitions

= < <= > >= <>

Fill in the Blanks

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

IF Mark __ 0 THEN OUTPUT "Not zero" ENDIF

IsAdult ← Age _ 17

IF Age __ 12 THEN OUTPUT "Child" ENDIF

IF Colour _ "Red" THEN OUTPUT "Stop" ENDIF

WHILE Count _ 10 DO Count ← Count + 1 ENDWHILE

Spot the Error

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

Question 1

A INPUT Age

B IF Age => 18 THEN

C OUTPUT "Adult"

D ENDIF

Question 2

A INPUT Guess

B IF Guess != 7 THEN

C OUTPUT "Wrong"

D ENDIF

Question 3

A INPUT Mark

B IF Mark > 50 THEN

C OUTPUT "50 or more: pass"

D ENDIF

Question 4

A INPUT Money

B Cost ← 5

C IF Money <= Cost THEN

D OUTPUT "Can buy"

E ENDIF

Question 5

A WHILE Lives < 0 DO

B Lives ← Lives - 1

C ENDWHILE

D OUTPUT "Game over"

Answer Key

Relational operators

Section A: Quick Questions

A — BOOLEAN (TRUE or FALSE)

A — <>

B — TRUE

B — FALSE

A — Mark >= 40

Section B: Match the Pairs

Age <> 18 → TRUE when Age is not equal to 18, otherwise FALSE

Score >= 50 → TRUE when Score is 50 or more, so 50 itself gives TRUE

Check that Mark is below 40 only, so a Mark of exactly 40 gives FALSE → Mark < 40

Check whether Password is exactly the same as the stored value Secret → Password = Secret

IF Age != 18 THEN → != is not a pseudocode operator. 'Not equal to' is written <>, so it should be IF Age <> 18 THEN.

IF Age < 18 THEN // must be 18 or over to vote → The boundary is wrong. A person aged exactly 18 should be allowed, so the test should be Age >= 18 and not Age < 18.

Section C: Definitions

= < <= > >= <> — Relational operators compare two values and give a BOOLEAN result (TRUE or FALSE). = equal, <> not equal, < less than, <= less or equal, > greater than, >= greater or equal.

Section D: Fill in the Blanks

IF Mark <> 0 THEN
  OUTPUT "Not zero"
ENDIF

IsAdult ← Age > 17

IF Age <= 12 THEN
  OUTPUT "Child"
ENDIF

IF Colour = "Red" THEN
  OUTPUT "Stop"
ENDIF

WHILE Count < 10 DO
  Count ← Count + 1
ENDWHILE

Section E: Spot the Error

B — => is not a relational operator in pseudocode. 'Greater than or equal to' is written >=, so the line should be IF Age >= 18 THEN.

B — Pseudocode uses <> for 'not equal to', not !=. The line should be IF Guess <> 7 THEN.

B — Boundary error. A mark of exactly 50 should pass, but > excludes 50. It should be >= 50 so the boundary value is included.

C — The operator points the wrong way. You can buy the item when Money is greater than or equal to Cost, so it should be IF Money >= Cost THEN.

A — Lives is never less than 0 while the player is still alive, so the condition is FALSE at once and the loop never runs. It should be WHILE Lives > 0 DO.