Assignment ← versus comparison =

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Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which line stores the value 5 in the variable Score?

A Score ← 5

B Score = 5

2. In this line, what does = do? IF Score = 5 THEN

A Tests whether Score is equal to 5

B Stores 5 in Score

3. Which is the correct way to write an assignment in 0478 pseudocode?

A Total = Total + 1

B Total ← Total + 1

4. What result does the condition Score = 5 give when Score holds 7?

A Score becomes 5

B FALSE

5. Which condition correctly tests that Score is NOT equal to 10?

A IF Score <> 10 THEN

B IF Score ← 10 THEN

Match the Pairs

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

Left column		Right column
1Score ← 5		AUses the assignment arrow inside a condition. A condition must test equality with =, so it should be IF Score = 5 THEN.
2IF Score = 5 THEN		BStores the value 5 in the variable Score (assignment)
3Use <> to test that two values are not equal		CIF Score <> 5 THEN
4Assignment changes the stored value of a variable, so Lives goes down by one		DLives ← Lives - 1
5Score = 5		ETests whether Score is equal to 5, giving TRUE or FALSE
6IF Score ← 5 THEN		FUses = to store a value. In 0478 pseudocode = is only for comparison, so assignment must be written Score ← 5.

Definitions

Score ← 5

Fill in the Blanks

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

Score _ 5

IF Score _ 5 THEN

IF Lives __ 0 THEN

Count ← 0 Count _ Count + 1

REPEAT INPUT Guess UNTIL Guess _ Secret

Spot the Error

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

Question 1

A Score = 0

B INPUT Guess

C IF Guess = 5

D THEN

E Score ← 10

F ENDIF

Question 2

A DECLARE Age : INTEGER

B INPUT Age

C IF Age ← 18

D THEN

E OUTPUT "Adult"

F ENDIF

Question 3

A Attempts ← 0

B INPUT Code

C WHILE Code <> 1234 DO

D Attempts = Attempts + 1

E INPUT Code

F ENDWHILE

Question 4

A INPUT Pin

B Tries ← 1

C IF Pin != 1234

D THEN

E OUTPUT "Wrong PIN"

F ENDIF

Question 5

A 3 ← Lives

B INPUT Hit

C IF Hit = "Y"

D THEN

E Lives ← Lives - 1

F ENDIF

Answer Key

Assignment ← versus comparison =

Section A: Quick Questions

A — Score ← 5

A — Tests whether Score is equal to 5

B — Total ← Total + 1

B — FALSE

A — IF Score <> 10 THEN

Section B: Match the Pairs

Score ← 5 → Stores the value 5 in the variable Score (assignment)

IF Score = 5 THEN → Tests whether Score is equal to 5, giving TRUE or FALSE

Use <> to test that two values are not equal → IF Score <> 5 THEN

Assignment changes the stored value of a variable, so Lives goes down by one → Lives ← Lives - 1

Score = 5 → Uses = to store a value. In 0478 pseudocode = is only for comparison, so assignment must be written Score ← 5.

IF Score ← 5 THEN → Uses the assignment arrow inside a condition. A condition must test equality with =, so it should be IF Score = 5 THEN.

Section C: Definitions

Score ← 5 — ← stores a value in a variable, so Score ← 5 saves 5 in Score. = only tests if two values are equal, as in IF Score = 5, and gives TRUE or FALSE. <> tests not equal.

Section D: Fill in the Blanks

Score ← 5

IF Score = 5 THEN

IF Lives <> 0 THEN

Count ← 0
Count ← Count + 1

REPEAT
  INPUT Guess
UNTIL Guess = Secret

Section E: Spot the Error

A — Storing a value in a variable needs the assignment arrow, so it should be Score ← 0. A single = only tests whether two values are equal.

C — An IF condition must test a value, so it needs = to compare. It should be IF Age = 18. The ← arrow would try to store 18 in Age.

D — This line stores a new value, so it needs the assignment arrow: Attempts ← Attempts + 1. Using = only compares and does not change Attempts.

C — In 0478 pseudocode, not equal is written <>, not !=. The line should be IF Pin <> 1234.

A — The variable goes on the left of the arrow and the value on the right. It should be Lives ← 3, which stores 3 in Lives.