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Programming concepts

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Question 3

The two subroutines in Figure 1 and Figure 2 are designed to count how many times a population P P\,P can be halved before it falls to 1 or below.

Figure 1

SUBROUTINE countHalvings(P)
  count ← 0
  WHILE P > 1
    P ← P / 2
    count ← count + 1
  ENDWHILE
  OUTPUT count
ENDSUBROUTINE

Figure 2

SUBROUTINE countHalvings(P)
  count ← 0
  REPEAT
    P ← P / 2
    count ← count + 1
  UNTIL P ≤ 1
  OUTPUT count
ENDSUBROUTINE

Describe two differences in the way the loops in Figure 1 and Figure 2 operate.

[3]
Markscheme

Programming concepts Questions

  1. GCSE
  2. /Computer Science
  3. /Programming concepts

298 exam-style questions on AQA GCSE Computer Science Programming concepts. Each one has a worked solution and a mark scheme showing where the marks go.

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