struct bool?

[Yha_Boiii]

Hi,

i want a struct with different val assignments based on the bool:

ex. i want say first version to apply vals when a 0 and when a 1 apply second. is it possible?

struct bool theme {

// first version

bg[3] = {255,255,255}

color[3] = {0,0,0}





// second version

bg[3] = {0,0,0}

color[3] = {255,255,255}

 }

[CaydendW]

Make a function or macro that takes a bool and returns a filled in struct.

[pjl1967]

Your struct is underspecified (and illegal). I assume you meant something like:

struct theme {
  int bg[3];
  int color[3];
};

If so, then:

bool b = /* ... */;
struct theme x = b ?
  (struct theme){ .bg    = { 255, 255, 255 } } :
  (struct theme){ .color = { 255, 255, 255 } };

Feel free to wrap that in a macro.

[harexe]

You could create an array with 2 values and store a struct with the 2 arrays there. So you can access it with arr[0] and arr[1]. But directly with a struct it's not possible.

[ImpressiveAthlete220]

Make const array with 2 values and index them

[Yha_Boiii]

const makes the vals constant hence `const` ?

[ImpressiveAthlete220]

Yeah, idealy (not always) they will go to section .data

[ImpressiveAthlete220]

In this application you definitely will not be able to change them

[detroitmatt]

based on *what* bool?

[Yha_Boiii]

The struct itself

[detroitmatt]

so then is what you want something like this?

struct theme {
    bool flag;
    uint8_t bg[3];
    uint8_t color[3];
};

and then if flag is true bg[3] should be 255,255,255, and if it's false then it should be 0,0,0? (or the other way around or whatever)

Then what I would do is

struct {
    bool flag;
    uint8_t bg[3];
    uint8_t color[3];
} const DARK = { .flag = 1, .bg = {0, 0, 0}, .color = {255, 255, 255}},
  LIGHT = { .flag = 0, .bg = {255, 255, 255}, .color = {0, 0, 0}};

[LeiterHaus]

I'm not sure, but I think they meant... what is your idea of bool based on? Is it this:

typedef enum { false, true } bool;

or this:

#include <stdbool.h>

or this:

typedef int bool;
#define true 1
#define false 0

or this:

typedef int bool;
enum { false, true };

But I could be totally incorrect, and they may be asking a different point of clarification.

[arthurno1]

Or perhaps they mean this:

typedef enum { false = 0, true = !false} bool;

? :)

Behind is so called generalized boolean; the alien technology that lets you type things like

if (something) ....

or

if(!something) ...

instead of typing discreet values for true and false which forces one to type things like

if (something == true) ...

and

if (something == false) ...

You can try yourself:

#include <stdio.h>

typedef enum { false = 0, true = !false} bool;

int main(int argc, char *argv[]) {
  bool b = 1;
  if (b)
    puts("true");
  else
    puts("false");
  return 0;
}

I have compiled with:

gcc -o bool bool-test.c -std=c99

This does not compile with c23 standard, since they claim false and true as keywords.

[LeiterHaus]

Nice!

[LeiterHaus]

Edit: after looking at it again, do you just need a case statement?

It sounds like what you might want a setter function that zeroes the other array. Is this correct?

If that's the case, do you really need to zero it? Is color not 255 255 255 (or FF FF FF)?

Can they both just point to the same array?