array of pointers to array of pointers in C

Question

I have an API which will take triple pointer as an input as below. extern int myAPI(int ***myData);

Internally "myData" is treated as array of pointer to array of pointers.

So now in another function, i need to call this myAPI. But i am not able to build the array of pointer to array of pointers. Can you please someone help?

I tried similar to below snippet of code. But seen type mismatch compilation error.

int i[10];
int j[10];
int *k[10];
int *l[10];
int *(*m[])[2];
int a = 0;
for (a = 0; a < 10; a++) {
    k[a] = &(i[a]);
    l[a] = &(j[a]);
}

m[0] = k;
m[1] = l;

a = myAPI(m);

I doubt this int *(*m[])[2]; even compiles. It attempts to declare an array of unspecified size without an initializer. — StoryTeller - Unslander Monica
– StoryTeller - Unslander Monica, Commented Dec 4, 2016 at 6:59
int myAPI(int ***myData); expects a pointer to pointer to pointer of int, — alk
– alk, Commented Dec 4, 2016 at 7:33
Just a reminder: you got two answer. If anyone helped, you should accept it. — too honest for this site
– too honest for this site, Commented Dec 5, 2016 at 1:34

too honest for this site · Accepted Answer · 2017-01-25 15:32:40Z

2

So you want an "array 10 of pointer to array of pointer 20 to int" (you have to specify the dimensions for all but functions arguments where you can omit the outermost dimension only).

That would be:

int *(*a[10])[20];

For such constructs, cdecl is very helpful. The line in quotes is the declaration for the tool.

Note this is what you asked for. Which is not necessarily what you really need. Often such complex constructs are a symptom of a severe design flaw. You might want to reconsider your program code.

edited Jan 25, 2017 at 15:32

answered Dec 4, 2016 at 7:31

too honest for this site

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Comments

logan rakai · Accepted Answer · 2016-12-04 07:01:43Z

1

Try changing the declaration of m to

int **m[2];

answered Dec 4, 2016 at 7:01

logan rakai

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3 Comments

too honest for this site Over a year ago

That's an array of pointers to pointers. OP wants an array of pointers to array of pointers!

alk Over a year ago

@Olaf: Passing int **m[something] to myAPI(int ***myData); would be correct. Though I agree there are no pointers to any array involved.

too honest for this site Over a year ago

@alk: That because the array decays, but as asked, OP wants something different for whatever reason. As I wrote: this might not be what OP should use. A 3-(or more)star pointer is typcally an indicator of bad desing.

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