asmhatreandClaude Sonnet 5
af615cc17c
Silent int/long overflow reproduced with real numbers, the Math *Exact() family (addExact/subtractExact/multiplyExact/incrementExact/decrementExact/ negateExact/toIntExact/absExact) with the abs(MIN_VALUE) trap absExact exists to catch, widening to long vs BigInteger, and the XOR-based overflow bit trick Math.addExact uses internally, cross-checked against BigInteger ground truth over 100k random int pairs per JUnit repeat. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01FhzLY5p6okFva3qsnsRyvM
16 lines
894 B
Plaintext
16 lines
894 B
Plaintext
$ java OverflowBitTrickDemo
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=== Hand-rolled overflow detector vs. known cases ===
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2000000000 + 2000000000 -> raw int result -294967296, overflow detected: true
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2000000000 + -1000000000 -> raw int result 1000000000, overflow detected: false
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2147483647 + 1 -> raw int result -2147483648, overflow detected: true
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-2147483648 + -1 -> raw int result 2147483647, overflow detected: true
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100 + 200 -> raw int result 300, overflow detected: false
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=== Cross-checked against Math.addExact() on the same inputs ===
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2000000000 + 2000000000: bit-trick says overflow=true, Math.addExact() agrees=true
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2000000000 + -1000000000: bit-trick says overflow=false, Math.addExact() agrees=true
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2147483647 + 1: bit-trick says overflow=true, Math.addExact() agrees=true
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-2147483648 + -1: bit-trick says overflow=true, Math.addExact() agrees=true
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100 + 200: bit-trick says overflow=false, Math.addExact() agrees=true
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