Question

I am writing a C program. I want a variable that I can access as a char but I can also access the specific bits of. I was thinking I could use a union like this…

typedef union 
{
    unsigned char status;
    bit bits[8];
}DeviceStatus;

but the compiler doesn’t like this. Apparently you can’t use bits in a structure.
So what can I do instead?

Answer 1

Sure, but you actually want to use a struct to define the bits like this

typedef union
{
  struct
  {
    unsigned char bit1 : 1;
    unsigned char bit2 : 1;
    unsigned char bit3 : 1;
    unsigned char bit4 : 1;
    unsigned char bit5 : 1;
    unsigned char bit6 : 1;
    unsigned char bit7 : 1;
    unsigned char bit8 : 1;
  }u;
  unsigned char status;
}DeviceStatus;

Then you can access for DeviceStatus ds; you can access ds.u.bit1. Also, some compilers will actually allow you to have anonymous structures within a union, such that you can just access ds.bit1 if you ommit the u from the typedef.