Why is std::bitset<8> 4 bytes big?

Question

It seems for std::bitset<1 to 32>, the size is set to 4 bytes. For sizes 33 to 64, it jumps straight up to 8 bytes. There can\'t be any overhead because std::bitset<

Answer 1

I had the same feature in Aix and Linux implementations. In Aix, internal bitset storage is char based:

typedef unsigned char _Ty;
....
_Ty _A[_Nw + 1];

In Linux, internal storage is long based:

typedef unsigned long _WordT;
....
_WordT            _M_w[_Nw];

For compatibility reasons, we modified Linux version with char based storage

Check which implementation are you using inside bitset.h