OTHERWISE in a CASE statement (8.1b)

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Quick Questions

Shade in the A or B circle for each question.

1. Where does OTHERWISE go in a CASE statement?

A As the last clause, after all the listed values

B As the first clause, before the listed values

2. When does the OTHERWISE clause run?

A Every time the CASE statement runs

B When the variable matches none of the listed values

3. Choice is 7 and the CASE only lists 1, 2 and 3, with no OTHERWISE. What happens?

A Nothing happens, no clause runs

B The program stops with an error message

4. Which line is the correct way to write an OTHERWISE clause?

A OTHERWISE OUTPUT "Invalid choice" ELSE

B OTHERWISE : OUTPUT "Invalid choice"

5. Choice is 2 and the CASE has 2 : OUTPUT "Option 2" and OTHERWISE : OUTPUT "Invalid choice". What is output?

A Option 2

B Option 2 and Invalid choice

Match the Pairs

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

Left column		Right column
1OTHERWISE : OUTPUT "Invalid choice"		ARuns and displays an error message when the CASE variable matches none of the listed values
2CASE OF Choice 1 : OUTPUT "Start" 2 : OUTPUT "Quit" ENDCASE		BOTHERWISE is placed before the listed value. It must be the last clause, so move it below 1 : OUTPUT "Start".
3OTHERWISE must be the last clause, placed after all the listed values and just before ENDCASE		CThe colon is missing after OTHERWISE. It should be OTHERWISE : OUTPUT "Invalid choice".
4Use OTHERWISE to catch invalid menu choices and tell the user		DCASE OF Grade 'A' : OUTPUT "Top" 'B' : OUTPUT "Good" OTHERWISE : OUTPUT "Try again" ENDCASE
5CASE OF Choice OTHERWISE : OUTPUT "Invalid choice" 1 : OUTPUT "Start" ENDCASE		EA CASE with no OTHERWISE, so nothing happens if Choice is 3
6OTHERWISE OUTPUT "Invalid choice"		FOTHERWISE : OUTPUT "Invalid choice"

Definitions

OTHERWISE

Fill in the Blanks

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

CASE OF Choice 1 : OUTPUT "Play" _________ : OUTPUT "Invalid choice"

1 : OUTPUT "Play" OTHERWISE : ______ "Invalid choice" ENDCASE

2 : OUTPUT "Quit" OTHERWISE : OUTPUT "Invalid choice" _______

CASE __ Menu OTHERWISE : OUTPUT "Invalid choice" ENDCASE

3 : OUTPUT "Exit" _________ : OUTPUT "Invalid choice" ENDCASE

Spot the Error

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

Question 1

A CASE OF Choice

B 1 OUTPUT "Start"

C OTHERWISE : OUTPUT "Error"

D ENDCASE

Question 2

A CASE Menu

B 1 : OUTPUT "Play"

C 2 : OUTPUT "Quit"

D OTHERWISE : OUTPUT "Error"

E ENDCASE

Question 3

A CASE OF Day

B 1 : OUTPUT "Mon"

C 2 : OUTPUT "Tue"

D OTHERWISE OUTPUT "Error"

E ENDCASE

Question 4

A CASE Grade OF

B "A" : OUTPUT "Top"

C "B" : OUTPUT "Good"

D OTHERWISE : OUTPUT "Error"

E ENDCASE

Question 5

A CASE OF Choice

B 1 : OUTPUT "Start"

C ELSE : OUTPUT "Error"

D ENDCASE

Answer Key

OTHERWISE in a CASE statement (8.1b)

Section A: Quick Questions

A — As the last clause, after all the listed values

B — When the variable matches none of the listed values

A — Nothing happens, no clause runs

B — OTHERWISE : OUTPUT "Invalid choice"

A — Option 2

Section B: Match the Pairs

OTHERWISE : OUTPUT "Invalid choice" → Runs and displays an error message when the CASE variable matches none of the listed values

CASE OF Choice 1 : OUTPUT "Start" 2 : OUTPUT "Quit" ENDCASE → A CASE with no OTHERWISE, so nothing happens if Choice is 3

OTHERWISE must be the last clause, placed after all the listed values and just before ENDCASE → CASE OF Grade 'A' : OUTPUT "Top" 'B' : OUTPUT "Good" OTHERWISE : OUTPUT "Try again" ENDCASE

Use OTHERWISE to catch invalid menu choices and tell the user → OTHERWISE : OUTPUT "Invalid choice"

CASE OF Choice OTHERWISE : OUTPUT "Invalid choice" 1 : OUTPUT "Start" ENDCASE → OTHERWISE is placed before the listed value. It must be the last clause, so move it below 1 : OUTPUT "Start".

OTHERWISE OUTPUT "Invalid choice" → The colon is missing after OTHERWISE. It should be OTHERWISE : OUTPUT "Invalid choice".

Section C: Definitions

OTHERWISE — The last clause of a CASE statement. It runs when the variable matches none of the listed values, e.g. OTHERWISE : OUTPUT "Invalid choice". Without it, nothing happens if no value matches.

Section D: Fill in the Blanks

CASE OF Choice
  1 : OUTPUT "Play"
  OTHERWISE : OUTPUT "Invalid choice"

  1 : OUTPUT "Play"
  OTHERWISE : OUTPUT "Invalid choice"
ENDCASE

  2 : OUTPUT "Quit"
  OTHERWISE : OUTPUT "Invalid choice"
ENDCASE

CASE OF Menu
  OTHERWISE : OUTPUT "Invalid choice"
ENDCASE

  3 : OUTPUT "Exit"
  OTHERWISE : OUTPUT "Invalid choice"
ENDCASE

Section E: Spot the Error

B — Each CASE clause needs a colon between the value and the statement. It should be 1 : OUTPUT "Start".

A — A CASE statement starts with CASE OF followed by the variable. OF is missing; it should be CASE OF Menu. Without it, the OTHERWISE clause has no valid CASE to belong to.

D — OTHERWISE must be followed by a colon, just like the value clauses. It should be OTHERWISE : OUTPUT "Error".

A — The keywords come first, then the variable: CASE OF Grade. The words are in the wrong order. Then OTHERWISE can catch any grade that is not A or B.

C — ELSE belongs to IF statements. The last CASE clause that runs when no value matches is OTHERWISE. It should be OTHERWISE : OUTPUT "Error".