typedef struct {
bool a: 1;
bool b: 1;
bool c: 1;
bool d: 1;
bool e: 1;
bool f: 1;
bool g: 1;
bool h: 1;
} __attribute__((__packed__)) not_if_you_have_enough_booleans_t;
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You beat me to it!
Or just std::bitset<8>
for C++.
Bit fields are neat though, it can store weird stuff like a 3 bit integer, packed next to booleans
Depending on the language
And compiler. And hardware architecture. And optimization flags.
As usual, it's some developer that knows little enough to think the walls they see around enclose the entire world.
I set all 8 bits to 1 because I want it to be really true.
01111111 = true
11111111 = negative true = false
Then you need to ask yourself: Performance or memory efficiency? Is it worth the extra cycles and instructions to put 8 bools in one byte and & 0x bitmask the relevant one?
Sounds like a compiler problem to me. :p
A lot of times using less memory is actually better for performance because the main bottleneck is memory bandwidth or latency.
Back in the day when it mattered, we did it like
#define BV00 (1 << 0)
#define BV01 (1 << 1)
#define BV02 (1 << 2)
#define BV03 (1 << 3)
...etc
#define IS_SET(flag, bit) ((flag) & (bit))
#define SET_BIT(var, bit) ((var) |= (bit))
#define REMOVE_BIT(var, bit) ((var) &= ~(bit))
#define TOGGLE_BIT(var, bit) ((var) ^= (bit))
....then...
#define MY_FIRST_BOOLEAN BV00
SET_BIT(myFlags, MY_FIRST_BOOLEAN)
Edit - oops, responded to wrong comment...
The 8-bit Intel 8051 family provides a dedicated bit-addressable memory space (addresses 20h-2Fh in internal RAM), giving 128 directly addressable bits. Used them for years. I'd imagine many microcontrollers have bit-width variables.
bit myFlag = 0;
Or even return from a function:
bit isValidInput(unsigned char input) { // Returns true (1) if input is valid, false (0) otherwise return (input >= '0' && input <= '9'); }
In the industrial automation world and most of the IT industry, data is aligned to the nearest word. Depending on architecture, that's usually either 16, 32, or 64 bits. And that's the space a single Boolean takes.
std::vector<bool>
fits eight booleans into one byte.
auto v = std::vector<bool>(8);
bool* vPtr = v.data;
vPtr[2] = true;
// KABOOM !!!
I've spent days tracking this bug... That's how I learned about bool specialisation of std::vector.
It's far more often stored in a word, so 32-64 bytes, depending on the target architecture. At least in most languages.
if wasting a byte or seven matters to you, then then you need to be working in a lower level language.
It's 7 bits....
Pay attention. 🤪
I have a solution with a bit fields. Now your bool is 1 byte :
struct Flags {
bool flag0 : 1;
bool flag1 : 1;
bool flag2 : 1;
bool flag3 : 1;
bool flag4 : 1;
bool flag5 : 1;
bool flag6 : 1;
bool flag7 : 1;
};
Or for example:
struct Flags {
bool flag0 : 1;
bool flag1 : 1:
int x_cord : 3;
int y_cord : 3;
};
Joke’s on you, I always use 64 bit wide unsigned integers to store a 1 and compare to check for value.