C Access 2D char array via Pointer

char **a_ptr = &ary; - this makes no sense. char** a_ptr is a pointer to a pointer. What you need is a pointer to an array. The following will do:

char (*a_ptr)[8] = ary; // also don't take the address of the array

If you're trying to print the pointer address, printf has a format for this %p. Replace your 0x%xs with %p.

I've edited your code as follows and my compiler no longer issues warnings:

#include <stdio.h>
#include <string.h>

int main()
{
    char ary[5][8];
    char temp[8];
    int i;

    char (*a_ptr)[8] = ary;

    for(i=0; i<5; i++)
    {
        sprintf(temp, "0x10%d" , i);
        strcpy(ary[i] , temp);
        printf("~~~%s@%p == %p" , ary[i] , &ary[i] , (a_ptr + i));

    }

    for(i=0; i<5; i++)
    {
        printf("~~~%s@%p" , *(a_ptr + i) ,  (a_ptr + i));
    }

    return 0;
}

And now my output is:

$ ./a.out 
~~~0x100@0xbfc77a74 == 0xbfc77a74~~~0x101@0xbfc77a7c == 0xbfc77a7c~~~0x102@0xbfc77a84 == 0xbfc77a84~~~0x103@0xbfc77a8c == 0xbfc77a8c~~~0x104@0xbfc77a94 == 0xbfc77a94~~~0x100@0xbfc77a74~~~0x101@0xbfc77a7c~~~0x102@0xbfc77a84~~~0x103@0xbfc77a8c~~~0x104@0xbfc77a94

Is this what you were hoping to get?

Some code that relies only on pointers and no arrays:

#include <stdio.h>
#include <string.h> /* for strcpy */
#include <stdlib.h> /* for free and malloc */

int main()
{

    char** two_d = malloc(sizeof(char*) * 5); /* allocate memory for 5 pointers to pointers */

    int i;
    for(i = 0; i < 5; i++) /* for each of the five elements */
    {
        two_d[i] = malloc(2); /* allocate memory to each member of two_d for a 2 char string */

        strcpy(two_d[i], "a"); /* store data in that particular element */

        printf("%s has address of %p\n", two_d[i], &two_d[i]); /* print the contents and the address */

        free(two_d[i]); /* free the memory pointer to by each pointer */
    }

    free(two_d); /* free the memory for the pointer to pointers */

    return 0;
}