戯術者の日記

struct foo {
  int a: 1;    // 1ビットの領域
  int b: 3;    // 3ビットの領域
  int c: 2;    // 2ビットの領域
};

struct fromdata {
  unsigned char first;
  unsigned char second;
  unsigned char third;
};

struct todata {
  unsigned first: 6;
  unsigned second: 6;
  unsigned third: 6;
  unsigned forth: 6;
};

union base64 {
  struct fromdata from;
  struct todata to;
};

int main() {
  printf("from: %d\n", sizeof(struct fromdata));
  printf("to: %d\n", sizeof(struct todata));
  return 0;
}

from: 3
to: 4