QA·C Help - 0457

	0457	[C] The address-of operator '&' cannot be applied to a bit-field.

Constraint violations		REFERENCE - ISO:C90-6.3.3.2 Address and Indirection Operators - Constraints

This is a constraint error

It might be possible to take the address of the struct/union which contains the bit-field, but it is never possible to take the address of a bit-field itself. A bit-field, by definition, can occupy part or all of a byte or word. The & (address of) operator returns the addressable location of an object in terms of bytes and so cannot specify exactly the bit-field location within a byte or word. For example:


/*PRQA S 2211,3198,3199,3203,3621 ++*/

struct flags {
   unsigned int hi:1;
   unsigned int lo:1;
   unsigned int ins:1;
   unsigned int ovr:1;
};

int main(void)
{
   struct flags f;
   int *ip;
   unsigned int i;

   f.hi = 0;
   f.lo = 0;
   f.ins = 0;
   f.ovr = 0;


   ip = &(f.hi);           /* Message 0457 */
   ip = &f.lo;             /* Message 0457 */

   i = f.ins;

   return 0;
}

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