Thread: What does the : indicate in a struct?

Code:

typedef struct
{
	uint8_t				bB0:1;	
	uint8_t				bB1:1;	
	uint8_t				bB2:1;	
	uint8_t				bB3:1;	
	uint8_t				bB4:1;	
	uint8_t				bB5:1;	
	uint8_t				bB6:1;	
	uint8_t				bB7:1;
}testStruct

What does the : indicates in the above struct? Does it mean 1 bit for each of them and total up to 8 bits?

Originally Posted by Edelweiss

Code:

typedef struct
{
	uint8_t				bB0:1;	
	uint8_t				bB1:1;	
	uint8_t				bB2:1;	
	uint8_t				bB3:1;	
	uint8_t				bB4:1;	
	uint8_t				bB5:1;	
	uint8_t				bB6:1;	
	uint8_t				bB7:1;
}testStruct

What does the : indicates in the above struct? Does it mean 1 bit for each of them and total up to 8 bits?

In addition to Fordy's good advice...

Yes, that's what it means. As 1 bit veriables each of the elements has only 2 states... 0 or 1, usually used as on and off or true and false.
An alternate form of bitfields can look like this...

Code:

typedef struct
{
   uint8_t  bB0:1,	
            bB1:1,
            bB2:1,	
            bB3:1,	
            bB4:1,	
            bB5:1,	
            bB6:1,	
            bB7:1;
}testStruct

But they amount to the same thing...

You should also note that not all compilers support uint8_t as a bitfield. The more common root is unsigned integer.