Strange Behavior When Using Union with Bit Fields in C
I'm experiencing unexpected behavior when trying to read from a union containing bit fields. I have the following union and struct defined: ```c #include <stdio.h> typedef union { struct { unsigned int a : 4; unsigned int b : 4; unsigned int c : 8; } bits; unsigned int value; } BitFieldUnion; ``` I then instantiate this union and set its fields like this: ```c int main() { BitFieldUnion u; u.bits.a = 0xA; // 1010 in binary u.bits.b = 0x5; // 0101 in binary u.bits.c = 0xF0; // 11110000 in binary printf("Combined value: %u\n", u.value); return 0; } ``` When I run this code, I expect the combined value to be a specific number based on the binary representation of the fields. However, I get an output that does not match my expectations. The printed value is `240`, which seems incorrect given that I manually set `a`, `b`, and `c`. I’ve tried changing the order of assignment and ensuring that the bit fields do not overlap, but the results remain consistent. I suspect it might be due to how the compiler is handling the union and bit fields, particularly regarding padding or bit alignment. I am using GCC version 10.2 on a Linux machine. Could this be an scenario with how unions and bit fields are implemented in C? Any insights on how to get the correct combined value would be appreciated.