Bit-fields “In-class initialization” results in “error: lvalue required as left operand of assignment”

Question

struct bitfield {
  int i = 0;  // ok
  int j : 8 = 0;  // error: lvalue required as left operand of assignment
};

What is the correct syntax to in

Answer 1

You can write a constructor with initializer list to give default values to your bitfields.

struct bitfield {
  int i;
  int j : 8;

  bitfield() : i(0), j(0) {};
};

You can also create read-only fields with default values.

struct _UserRegister1
{
  uint8_t _RES0 : 1;
  const uint8_t reserved1 : 1;
  uint8_t _HTRE : 1;
  const uint8_t reserved2 : 3;
  uint8_t _VDDS : 1;
  uint8_t _RES1 : 1;

  _UserRegister1() : reserved1(1), reserved2(7) {};
};