Styjun

I would like to declare a pointer to a 3d array in a manner that I could index it with one dimension less than original array, example: ptr[i][j]. I'm using some structure in which I would like this pointer to be stored so I could access it later.

I've done this with the 2d arrays but I declared a pointer to an array of pointers to 2d arrays:

typedef const unsigned char* ptrType;
const ptrType ptrArray[] = ...;

And this is what I'm trying for the 3d array:

typedef const unsigned char** ptrType;

typedef struct structP

 ptrType arrayPtr;
;

and in the main I'm doing something like this:

struct structP test;
test.arrayPtr = *myThreeDArray; 

when trying to access elements via pointer this is the only thing that compiler let me do:

&(test.arrayPtr[i][j]);

Also myThreeDArray is defined like this:

const unsigned char myThreeDArray[2][23][25] = ... ;

Doing it in a way that is described gives me unspected results at the output. Some garbage values.

Any ideas how to do this in a proper way?

What you seem to want is a pointer to a 2D array

For integers this could be like:

#include <stdio.h>

void print_3d(int (*p3d)[3][4])

 for (int i=0; i<2; ++i)
 for (int j=0; j<3; ++j)
 for (int k=0; k<4; ++k)
 printf("%d ", p3d[i][j][k]);


int main(int argc, char *argv[])

 int arr3d[2][3][4] = 
 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
 ;

 int (*p_to_arr3d)[3][4] = arr3d; // Get a pointer to int[3][4]
 print_3d(p_to_arr3d); // Use the pointer

Output:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 

In case you are dealing with strings, it could be like:

#include <stdio.h>

void print_3d(char (*p3d)[3][20])

 for (int i=0; i<2; ++i)
 for (int j=0; j<3; ++j)
 printf("%s ", p3d[i][j]);


int main(int argc, char *argv[])

 char arr3d[2][3][20] = 
 "this", "is", "just",
 "a", "little", "test"
 ;

 char (*p_to_arr3d)[3][20] = arr3d; // Get a pointer to char[3][20]
 print_3d(p_to_arr3d);

Output:

this is just a little test

Using the same syntax as above you can store the pointer in a struct:

struct myData

 char (*p_to_char_arr)[3][20];
 int (*p_to_int_arr)[3][4];
;