c++ - 如何将 unsigned long long 位分成 3 个整数，每个整数都有 [1-2, 3-5, 6-7] 位？

Question

有unsigned long long a如何将其位分成 3 个整数，每个整数都有 [1-2, 3-5, 6-7] 位？

Answer 1

unsigned long long a;
// bits 1 and 2 assuming 0 indexed
int first = static_cast<int>((a & (3ULL<<1))>>1);
// bits 3 and 5 assuming 0 indexed
int second = static_cast<int>((a & (3ULL << 3)) >> 3);
// bits 6 and 7 assuming 0 indexed
int third = static_cast<int>((a & (3ULL << 5)) >> 5);