Returning arrays

[uneven pulsar]

Curious about whether I'm just doing it wrong or if there's a better method, but I'm not quite sure how to make a function return an array.

For some reason, it hasn't quite worked for me, but it seems to work okay if I make it save the results to a given array and just have the function be a void

Though even then, it still seems unfortunate because I would have to have the array size beforehand, which at times seems computationally redundant in more complex cases

Is there a better solution? I've not much experience with C so I could just have the syntax wrong but I couldn't really find anything on it online

[dense crescent]

When your question is answered use !solved to mark the question as resolved.

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[uneven pulsar]

(I'm probably skipping a few steps in terms of learning but that's a pretty big pattern with me)

[valid jetty]

a function can't return an array, and you've already discovered the usual solution of "save the results to a given array and have the function be void"

it is possible to have a function return a struct or union that contains an array, but you still need to know the size ahead of time

[uneven pulsar]

That's unfortunate

[valid jetty]

you can allocate different sized arrays with malloc, but this is often much more "computationally redundant"

malloc is more "expensive" than you would expect

[uneven pulsar]

Oh well

[valid jetty]

there are some other options that all have their own problems, C does not do a good job with "different sized arrays"

[uneven pulsar]

An example of a thing I was trying was having a function that takes an input char array and returns a 2d array containing all combinations of the elements in that char array

So for example, function("abc") would return { "abc", "acb", "bac", "bca", "cab", "cba" }

The size for a char array of size N would be [N][N!]
Factorial functions seemed expensive to calculate twice

I'll try to look into seeing if malloc would work for something like that I suppose

Thanks

!solved

[dense crescent]

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[uneven pulsar]

Actually, I suppose I should ask for clarification before I crash my computer accidentally

[valid jetty]

i just mean that malloc and realloc and free are not only slower than most beginners expect them to be, but also use more memory

[uneven pulsar]

Yeah
Is the amount of memory it uses linear?

[valid jetty]

linear in the size of the allocation, although it will at least be rounded up to a multiple of 16 and possibly rounded up to a power of 2

[uneven pulsar]

That sounds harsh

[valid jetty]

it's not so bad, it means it's always more than 50% efficient, plus it means memory comes in standard sized blocks so it's more likely to be reusable

[uneven pulsar]

Fair enough

[valid jetty]

i see a lot of beginners on here worried about putting five or six pointers on the stack and my advice to you is don't worry about that

basically anything smaller than 1K on stack is not worth worrying about

[uneven pulsar]

It might take me a while to get used to active memory management
I only started learning a couple hours ago tho so it might grow on me considering my C# habits

[valid jetty]

the stack is like 1M no matter how much or how little you use it

[uneven pulsar]

1M bytes?

I suppose I won't run out soon then

[rich falcon]

[[laughs in microcontroller]]

[valid jetty]

i don't think this person was programming a microcontroller

not many microcontrollers i know of that use C#

[rich falcon]

but a good reason to start using C/C++ from C# is to do microcontrollers.

[uneven pulsar]

I had learned js for use with microcontrollers

[runic patrol]

std::array<const char*, 3> runFunc()
{
  return {"test", "array", "here"};
}

[uneven pulsar]

The syntax is suddenly lost on me

[uneven pulsar]

It looks a bit more like cpp than c

[runic patrol]

yes, it\s C++, apologies

struct Arr1
{
  const char* elements[3];
}

struct Arr1 runFunc()
{
  return {"test", "array", "return"};
}

here is the C equivalent

[valid jetty]

that isn't C

that's C++ still

[uneven pulsar]

[runic patrol]

struct Arr1
{
  const char* elements[3];
};

struct Arr1 runFunc()
{
    struct Arr1 result = {{"test", "array", "return"}};
  return result;
}

int main()
{

}

really

[lyric falcon]

generic chained array system ```c
typedef struct s_Carray
{
void* data; //void* is a generic type you can cast it to get the data
struct s_Carray* next;
}*Carray;

Carray create()
{
Carray out = malloc(sizeof(struct s_Carray));
out->next = NULL;
out->data = NULL;
return out;
}
void free_Carray(Carray in)
{
Carray temp = in;
while(temp != NULL)
{
if(temp->data != NULL)
{
free(data);
}
Carray temp2 = temp;
temp = temp->next;
free(temp2);
}
}

[valid jetty]

... you mean "linked list"