this post was submitted on 15 May 2025
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Programmer Humor

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[–] [email protected] 184 points 1 month ago (3 children)
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;
[–] [email protected] 43 points 1 month ago

You beat me to it!

[–] [email protected] 41 points 1 month ago* (last edited 1 month ago) (1 children)

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

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[–] [email protected] 16 points 1 month ago (1 children)

This was gonna be my response to OP so I'll offer an alternative approach instead:

typedef enum flags_e : unsigned char {
  F_1 = (1 << 0),
  F_2 = (1 << 1),
  F_3 = (1 << 2),
  F_4 = (1 << 3),
  F_5 = (1 << 4),
  F_6 = (1 << 5),
  F_7 = (1 << 6),
  F_8 = (1 << 7),
} Flags;

int main(void) {
  Flags f = F_1 | F_3 | F_5;
  if (f & F_1 && f & F_3) {
    // do F_1 and F_3 stuff
  }
}
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[–] [email protected] 142 points 1 month ago (1 children)
[–] [email protected] 153 points 1 month ago (14 children)

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.

[–] [email protected] 14 points 1 month ago (1 children)

Fucking lol at the downvoters haha that second sentence must have rubbed them the wrong way for being too accurate.

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[–] ricecake 135 points 1 month ago (4 children)

I set all 8 bits to 1 because I want it to be really true.

[–] [email protected] 95 points 1 month ago* (last edited 1 month ago) (8 children)

01111111 = true

11111111 = negative true = false

[–] [email protected] 48 points 1 month ago (3 children)
[–] [email protected] 28 points 1 month ago (3 children)
[–] [email protected] 22 points 1 month ago

100001111 = maybe not

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[–] [email protected] 34 points 1 month ago (4 children)

What if it's an unsigned boolean?

[–] [email protected] 25 points 1 month ago

Cthulhu shows up.

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[–] ricecake 12 points 1 month ago

Could also store our bools as floats.

00111111100000000000000000000000 is true and 10111111100000000000000000000000 is negative true.

Has the fun twist that true & false is true and true | false is false .

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[–] [email protected] 14 points 1 month ago (1 children)

TIL, 255 is the new 1.

Aka -1 >> 1 : TRUE

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[–] [email protected] 12 points 1 month ago

I was programming in assembly for ARM (some cortex chip) and I kid you not the C program we were integrating with required 255, with just 1 it read it as false

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[–] [email protected] 95 points 1 month ago (1 children)

string boolEnable = "True";

[–] [email protected] 40 points 1 month ago (1 children)
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[–] [email protected] 90 points 1 month ago (6 children)

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?

[–] ricecake 37 points 1 month ago

Sounds like a compiler problem to me. :p

[–] [email protected] 23 points 1 month ago (4 children)

A lot of times using less memory is actually better for performance because the main bottleneck is memory bandwidth or latency.

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[–] [email protected] 55 points 1 month ago (1 children)

Wait till you find out about alignment and padding

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[–] [email protected] 52 points 1 month ago (6 children)

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)

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[–] [email protected] 39 points 1 month ago* (last edited 1 month ago) (3 children)

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'); }

[–] [email protected] 17 points 1 month ago (4 children)

Nothing like that in ARM. Even microcontrollers have enough RAM that nobody cares, I guess.

[–] [email protected] 11 points 1 month ago

ARM has bit-banding specifically for this. I think it’s limited to M-profile CPUs (e.g. v7-M) but I’ve definitely used this before. It basically creates a 4-byte virtual address for every bit in a region. So the CPU itself can’t “address” a bit but it can access an address backed by only 1 bit of SRAM or registers (this is also useful to atomically access certain bits in registers without needing to use SW atomics).

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[–] [email protected] 13 points 1 month ago

We could go the other way as well: TI's C2000 microcontroller architecture has no way to access a single byte, let alone a bit. A Boolean is stored in 16-bits on that one.

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[–] [email protected] 39 points 4 weeks ago (1 children)

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.

[–] [email protected] 19 points 4 weeks ago (1 children)

That's why I primarily use booleans in return parameters, beyond that I'll try to use bitfields. My game engine's tilemap format uses a 32 bit struct, with 16 bit selecting the tile, 12 bit selecting the palette, and 4 bit used for various bitflags (horizontal and vertical mirroring, X-Y axis invert, and priority bit).

[–] [email protected] 29 points 4 weeks ago (6 children)

Bit fields are a necessity in low level networking too.

They're incredibly useful, I wish more people made use of them.

I remember I interned at a startup programming microcontrollers once and created a few bitfields to deal with something. Then the lead engineer went ahead and changed them to masked ints. Because. The most aggravating thing is that an int size isn't consistent across platforms, so if they were ever to change platforms to a different word length, they'd be fucked as their code was full of platform specific shenanigans like that.

/rant

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[–] [email protected] 34 points 1 month ago (1 children)
[–] [email protected] 11 points 1 month ago* (last edited 1 month ago)

Weird how I usually learn more from the humor communities than the serious ones... 😎

[–] [email protected] 32 points 1 month ago (2 children)

std::vector<bool> fits eight booleans into one byte.

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[–] [email protected] 27 points 1 month ago (11 children)

It's far more often stored in a word, so 32-64 bytes, depending on the target architecture. At least in most languages.

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[–] [email protected] 23 points 1 month ago (1 children)

if wasting a byte or seven matters to you, then then you need to be working in a lower level language.

[–] [email protected] 27 points 1 month ago (1 children)

It's 7 bits....

Pay attention. 🤪

[–] [email protected] 30 points 1 month ago (1 children)

7 bytes! Look at Mr. Moneybags here!

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[–] [email protected] 22 points 1 month ago (1 children)

Joke’s on you, I always use 64 bit wide unsigned integers to store a 1 and compare to check for value.

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[–] [email protected] 21 points 4 weeks ago (3 children)
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[–] [email protected] 21 points 1 month ago* (last edited 1 month ago) (1 children)

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;
};
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[–] [email protected] 17 points 1 month ago (1 children)
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[–] [email protected] 16 points 1 month ago (1 children)

just like electronic components, they sell the gates by the chip with multiple gates in them because it's cheaper

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[–] savedbythezsh 14 points 4 weeks ago (6 children)

Are you telling me that no compiler optimizes this? Why?

[–] [email protected] 34 points 4 weeks ago

It would be slower to read the value if you had to also do bitwise operations to get the value.

But you can also define your own bitfield types to store booleans packed together if you really need to. I would much rather that than have the compiler do it automatically for me.

[–] [email protected] 23 points 4 weeks ago (4 children)

Well there are containers that store booleans in single bits (e.g. std::vector<bool> - which was famously a big mistake).

But in the general case you don't want that because it would be slower.

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[–] [email protected] 13 points 4 weeks ago (3 children)

Wait until you hear about alignment

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[–] [email protected] 12 points 4 weeks ago (1 children)

This reminds me that I actually once made a class to store bools packed in uint8 array to save bytes.

Had forgotten that. I think i have to update the list of top 10 dumbest things i ever did.

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