A 2D Array in Action: a TV-watching Log — Arrays | IGCSE Computer Science

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 5% of your exam marks.

stable

Rare

Stable5%

1D array manipulation with FOR loops appears regularly in Paper 2. 4 to 6 marks.

Example — A parent records the minutes of TV watched by 4 children (Quinn, Lyla, Harry, Elias) over 5 weekdays (Monday to Friday). The data is held in a 2D array called minsWatched indexed with [Day, Child], where days 1 to 5 are Monday to Friday and children 1 to 4 are Quinn, Lyla, Harry and Elias respectively.

	1 (Quinn)	2 (Lyla)	3 (Harry)	4 (Elias)
1 Monday	34	67	89	78
2 Tuesday	56	43	45	56
3 Wednesday	122	23	34	45
4 Thursday	13	109	23	90
5 Friday	47	100	167	23

Now answer:

Lyla on Tuesday: OUTPUT minsWatched[2, 2] → outputs 43.
Harry on Friday: OUTPUT minsWatched[5, 3] → outputs 167.
Quinn on Wednesday: OUTPUT minsWatched[3, 1] → outputs 122.

Many questions of this kind appear in past papers. The trick is to remember the row-then-column order shown in the question and not to swap them by accident.

Calculating each child's weekly total

FOR Child ← 1 TO 4
   ChildTotal ← 0
   FOR Day ← 1 TO 5
      ChildTotal ← ChildTotal + minsWatched[Day, Child]
   NEXT Day
   OUTPUT "Child ", Child, ": ", ChildTotal, " minutes"
NEXT Child

For Quinn (Child 1): 34 + 56 + 122 + 13 + 47 = 272 minutes.

Finding the day with the most total viewing

DECLARE MaxTotal : INTEGER
DECLARE MaxDay : INTEGER
MaxTotal ← 0
MaxDay ← 0

FOR Day ← 1 TO 5
   DayTotal ← 0
   FOR Child ← 1 TO 4
      DayTotal ← DayTotal + minsWatched[Day, Child]
   NEXT Child
   IF DayTotal > MaxTotal THEN
      MaxTotal ← DayTotal
      MaxDay ← Day
   ENDIF
NEXT Day

OUTPUT "Highest day was ", MaxDay, " with ", MaxTotal, " minutes total"