29. Bit Field Operations-ii

Question.4

Two developers extract a 4-bit field from bits 4–7 of an 8-bit register:

Developer A — mask then shift:

uint8_t val = (reg & 0xF0) >> 4;

Developer B — shift then mask:

uint8_t val = (reg >> 4) & 0x0F;

Which is safer for general-purpose use in firmware?

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A is safer — masking first prevents garbage in upper bits
B is safer — it works correctly regardless of integer promotion or register width
Both are always identical in behavior
Neither is safe — both need an explicit cast

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