Paper II: Selection and Iteration

Question 1

What are selection functions for?

Answer 1

To make a decision between two or more options.

Question 2

What three statements represent selection in pseudocode?

Answer 2

IF
ELSE
ELIF or ELSEIF

Question 3

How do you use ELSE IF?

Answer 3

You embed the IF construct under the ELSE statement.

Question 4

How is selection represented in flowcharts?

Answer 4

With a rhombus shape that has the two options: YES and NO.

Question 5

What is iteration for?

Answer 5

Iteration i the process of repeating a set of instructions for a set amount of times or until the desired outcome is reached.

Question 6

What is count controlled iteration?

Answer 6

When the number of iterations is known before loop is started.

Question 7

What programming structure is used?

Answer 7

FOR loop
e.g.
FOR turns FROM 0 TO 3 DO
       SEND turns TO DISPLAY
END FOR

This will output 0, 1, 2 and 3

Question 8

How do you structure a FOR loop with a step?

Answer 8

FOR index FROM 2 TO 10 STEP 2 DO
SEND index TO DISPLAY
END FOR

This will output 2, 4, 6, 8 and 10

Question 9

FOR EACH structure?

Answer 9

SET scores TO [9, 6, 7, 3, 9]
FOR EACH score FROM scores DO
SEND score TO DISPLAY
END FOR

This will output 9, 6, 7, 3 and 9

Question 10

What is condition controlled iteration?

Answer 10

Used when the number of loops is determined by a condition.

Question 11

What programming structure is used?

Answer 11

SET number TO 0
WHILE number <> 3 DO
RECEIVE number FROM (INT)KEYBOARD
END WHILE

Question 12

REPEAT … UNTIL loops?

Answer 12

They continue until a condition becomes true.

e.g.
REPEAT
RECIEVE number FROM (INT)KEYBOARD
UNTIL number = 3

It will continue looping until 3 is entered

Question 13

REPEAT … TIMES?

Answer 13

This loop will be repeated the number of times indicated.

e.g.
REPEAT 10 TIMES
RECEIVE score FROM (INT)KEYBOARD
END REPEAT