Why there isn't a single bit data type in C/C++? [duplicate]

Question

This question already has answers here:

C++ : why bool is 8 bits long? (7 answers)

Closed 8 years ago.

For bool, it's 8 bit while has only true and false, why don't they make it single bit.

And I know there's bitset, however it's not that convenient, and I just wonder why?

Answer 1

The basic data structure at the hardware level of mainstream CPUs is a byte. Operating on bits in these CPUs require additional processing, i.e. some CPU time. The same holds for bitset.

Answer 2

Not exactly an answer to why there is not a native type. But you can get a 1-bit type inside of a struct like this:

struct A {
  int a : 1; // 1 bit wide
  int b : 1;
  int c : 2; // 2 bits
  int d : 4; // 4 bits
};

Thus, sizeof(A) == 1 could be if there wouldn't be the padding (which probably takes it to a multiple of sizeof(void*), i.e. maybe 4 for 32bit systems).

Note that you cannot get a pointer to any of these fields because of the reasons stated by the other people. That might also be why there does not exist a native type.