How do I pass an address of array of structs to a function?

Question

So I have this problem. I initialize one parameter of my array of structs, then I want to check it in another function. I checked, the address is the same as in the main(), but the vaule is just random. I don't know why, HELP!

int i;
STOL s[STOLY];
char choice[MAXSTRING] = "jupiiiii", ***p;
/*if ((p = (char ***) malloc(MAXSTRING * sizeof(char **))) == NULL)
    exit(-5);*/

for (i = 0; i < STOLY; i++)
    s[i].novy = 0;

while (strcmp(choice, "stop"))
{
    puts("Casnik alebo bar?");
   /* *p = nacitaj_choice();
    choice = *p;*/
    nacitaj_choice(choice);
    free(p);

    if (strcmp(choice, "casnik") == 0)
        zadaj_stol(0, &s); /*HERE I SEND THE ADDRESS*/
    if (strcmp(choice, "bar") == 0)
        zadaj_stol(1, &s);
}

and I want to check the novy in another function

    void zadaj_stol(int typ, STOL *p_s[STOLY])
{
    int stol;
    printf("Stol cislo: ");
    stol = (cislo_stola() - 1);
    if (!p_s[stol]->novy) /*HERE IS THE PROBLEM*/
        reset_stol(p_s[stol]);
    zadaj_udaj(typ, p_s[stol]);
    vypis_stol(p_s[stol]);
}

I checked, and p_s is the same as &s, but for some reason p_s[stol]->novy is always something like -3782126. btw stol is between 0 and 13

Because I can't answer my question yet, here is the partial solution that I've figured out. Problem is, it only works if the index of p_s is 0, ie p_s[0]->novy works fine, but p_s[1] give call stack, it doesn't know the address. I'm not sure why.

int main()
{
    int i;
    STOL s[STOLY], **p_s;
    if ((p_s = (STOL **) malloc(sizeof(STOL))) == NULL)
        return -5;
    *p_s = s;
    char choice[MAXSTRING] = "jupiiiii";

    for (i = 0; i < STOLY; i++)
        s[i].novy = 0;

    while (strcmp(choice, "stop"))
    {
        puts("Casnik alebo bar?");
        nacitaj_choice(choice);

        if (strcmp(choice, "casnik") == 0)
            zadaj_stol(0, p_s);
        if (strcmp(choice, "bar") == 0)
            zadaj_stol(1, p_s);
    }

    return 0;
}

void zadaj_stol(int typ, STOL **p_s)
{
    int stol;
    printf("Stol cislo: ");
    stol = (cislo_stola() - 1);
    if (!p_s[stol]->novy)
        reset_stol(p_s[stol]);
    zadaj_udaj(typ, p_s[stol]);
    vypis_stol(p_s[stol]);
}

Answer 1

Change this

void zadaj_stol(int typ, STOL *p_s[STOLY])
{
  int stol;
  printf("Stol cislo: ");
  stol = (cislo_stola() - 1);
  if (!p_s[stol]->novy) /*HERE IS THE PROBLEM*/
    reset_stol(p_s[stol]);
  zadaj_udaj(typ, p_s[stol]);
  vypis_stol(p_s[stol]);
}

be become this:

void zadaj_stol(int typ, STOL (*p_s)[STOLY])
{
  int stol;
  printf("Stol cislo: ");
  stol = (cislo_stola() - 1);
  if (!(*p_s)[stol].novy) 
    reset_stol((*p_s)[stol]);
  zadaj_udaj(typ, (*p_s)[stol]);
  vypis_stol((*p_s)[stol]);
}

Answer 2

只需在调用函数s位置将&s更改为s ，然后从函数的参数列表中删除[STOLY] 。

Answer 3

Just change &s to s to pass the array. You are getting the error error: invalid type argument of '->' because p_s is of type STOL* , which means p_s[stol] is of type STOL (not a pointer). The left side operand of -> should be a pointer. You can do:

if(!p_s[stol].novy) instead.

Answer 4

So yeah I solved it after a while. Just in case anyone has the same problem in the future, here is the solution. Because I had s[STOLY] , array of structures, s on its own is a pointer. Therefore, when I wanted to pass it to the zadaj_stol() function as a pointer, it should just be s . Then in zadaj_stol() function s was a pointer but s[stol] was a structure, therefore use the . notation. Then to pass it on as a pointer again, I used &s[stol] . Here is the sample code (I've changed a lot since then, but the principle applies.

int main()
{
    int i, io;
    STOL s[STOLY];

    char choice[MAXSTRING] = "jupiiiii"; /*random string*/

    for (i = 0; i < STOLY; i++) {
        s[i].novy = 1;
        s[i].ucet = 0;
    }

    while (strcmp(choice, "stop"))
    {
        puts("\n**********************************\n");
        puts("Vstup alebo vystup? (Pre navod napis help, pre ukoncenie stop)");
        nacitaj_choice(choice);
        if ((strcmp(choice, "vstup")) == 0) {
            io = 0;
            typ_vstup(s, io);
        }
        else if ((strcmp(choice, "vystup")) == 0) {
            io = 1;
            typ_vstup(s, io);

        }
        else if ((strcmp(choice, "help")) == 0)
            help();
    }
    ziskaj_obrat(s);
    getchar();
    return 0;
}

and the use that in function like this

void zadaj_stol(int typ, STOL p_s[], int io) /*nacita cislo_stola, ak potrebne zresetuje ho, a bud vola zadaj_udaj alebo vypis_stol*/
{
    int stol;
    printf("Stol cislo: ");
    stol = (cislo_stola() - 1);
    if (p_s[stol].novy)
        reset_stol(&p_s[stol]);
    if (!io)
        zadaj_udaj(typ, &p_s[stol]);
    else
        vypis_stol(typ, &p_s[stol]);
}

it's important to realise what is a value, and what is a pointer. Because I had an array s[14] , s is a pointer to the beginning of the array, s[whatever] is a value (structure in my case), and &s[whatever] is an address/pointer to the structure.