I am trying my hands on a C pointer literature. In one of the illustrations, I encountered the following code.

# include <stdio.h>

int main()
{
     static int a[]={0,1,2,3,4};
     static int *p[]={a, a+1, a+2, a+3, a+4};

     int **ptr;

     ptr =p;

     **ptr++;
     printf("%d %d %d\n", ptr-p, *ptr-a, **ptr);

     *++*ptr; 
     printf("%d %d %d\n", ptr-p, *ptr-a, **ptr);

     ++**ptr;
     printf("%d %d %d\n", ptr-p, *ptr-a, **ptr);

     return 0;
}

I receive the output as.

1 1 1
1 2 2
1 2 3

I am facing a problem in justifying this output. I made lot of boxes on a copy for easy grasp of the problem. I am able to justify the output 1 1 1, my trouble starts with the statement, *++*ptr.

Since, a unary operators are executed from right to left. So, *ptr would be tackled first, then the value at ptr would be incremented. After this increment, I am not sure what happens, the book says that somehow p is also incremented to point to the next element in this array. The output 1 2 2 can only be achieved through the increment of p.

I am not sure that this kind of question fits exactly on stackoverflow.
I tried my best, wasted at least 10 pages with boxes drawn over them.

Any clarification would be appreciated.

c arrays pointers
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