ITPEC IP October 2023 Question 6
ITPEC IP October 2023 — Question 6 of 100
To exchange A and B, first preserve A in TMP, then copy B into A, and finally copy the preserved value into B. The correct sequence is TMP ← A, A ← B, B ← TMP. If the original values are A = α and B = β, the final values become A = β and B = α.
Answer (b)
Why not others:
- (a) finishes with B ← A after A was overwritten, so both variables become the original B
- (c) saves B but finishes by restoring B from TMP, leaving both variables as the original B
- (d) saves B and then copies overwritten A back to B, again failing to preserve the original A
Key rule: Before overwriting the first variable, save its original value; the final assignment must restore that saved value into the second variable.
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