Java bit operations — which two expressions evaluate to the same result? Expressions: 1) 32/4 2) (8 >> 2) << 4 3) 2^5 4) 128 >>> 2 5) 2 >> 5 Assume int arithmetic and default operator precedence.
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A1 and 2
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B2 and 4
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C1 and 3
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D2 and 3
Answer
Correct Answer: 2 and 4
Explanation
Introduction / Context:This item tests knowledge of shift operators and clarifies that ^ is bitwise XOR, not exponentiation. You must determine which pair among the given expressions yields the same integer result.
Given Data / Assumptions:
- 32-bit signed
intarithmetic. >>is arithmetic right shift;<<is left shift;>>>is logical right shift;^is XOR.
Concept / Approach:Evaluate each expression explicitly. Compare the results to find equal pairs. Note that right-shifting 128 by 2 places (logical) gives 32. Composing shifts on 8 as shown produces another constant you can compute directly.
Step-by-Step Solution:
1) 32/4 = 8.2) (8 >> 2) << 4 → 8 >> 2 = 2; then 2 << 4 = 32.3) 2 ^ 5 → XOR of 2 and 5 = 7.4) 128 >>> 2 → logical right shift 128 by 2 = 32.5) 2 >> 5 → arithmetic right shift gives 0.Equal pair: expressions 2 and 4 (both 32).Verification / Alternative check:Quick mental binary: 128 is 1 at bit 7; shifting right 2 → bit 5 set → 32. For expression 2, 8 (bit 3) >> 2 → bit 1 (value 2); << 4 → bit 5 (value 32).
Why Other Options Are Wrong:
- Pairs including 1 or 5 do not match 32.
- Pair including 3 assumes XOR equals exponent; it does not.
Common Pitfalls:Confusing ^ with power and overlooking that logical vs arithmetic right shifts differ only for negative operands.
Final Answer:2 and 4