Bit Flags

[zb0S216C]

I understand bit-flags but I don't know how to create them. So far this is the only way I know how to create a bit-flag:

struct Bit_Flags
{
    int Flag_Failed:1;  // 1-bit flag.
} Bit_Flags;

Is this preprocessor define directive the same as the one above?

#define FLAG_FAILED:1 

I know how to use bitset, but, I'm just exploring alternatives.

[firedraco]

Erm, no, not really...I'm not sure what you think that define does, but at best is simply defines "FLAG_FAILED:1" and nothing else...

Btw, I'd change the int to bool, because by definition, a flag is only true or false. (Plus 1 bit can only be true or false anyway).

[hanst99]

You could use an int (here assuming an int is 32 bits large, but that's the case on most platforms and compilers anyways):

#define FLAG1 0x01
#define FLAG2 0x02
#define FLAG3 0x04
#define FLAG4 0x08
#define FLAG5 0x10
#define FLAG6 0x20
//and so on
int flags;
// set a flag:
flags = flags | FLAG1;
//check whether a flag is set or not
if(flags & FLAG1)
//check whether multiple flags are set
if(flags & (FLAG1 | FLAG2 | FLAG3))
//set all flags at once
flags = numeric_limits<unsigned int>::max();

[zb0S216C]

Thanks, Hanst. I was going to ask how I can test to see what flags were set, but, you already gave me an example. Thanks again, Hanst.