Thread: A question on arrays and pointers and right associativity

I've got another question that hinges on right associativity.

I got to the next chapter, on pointers and arrays, and was having some difficulty understanding the statements in this chart. I thought it might help if I added assignments to each of them to better understand what they mean.

I'm not sure if the natural language expressions I wrote back are correct. My additions are in blue highlight marks. Are they the correct natural language text for the corresponding blue expressions?

To get a better sense of my train of thought, here are the full notes I wrote down, which contain some of the book text. Uploaded the PDF to an external site since my PDF is bigger than allowed by the message board: https://www.pdf-archive.com/2017/01/02/and-combination/

http://i.cubeupload.com/qg1eLv.jpg

The last one doesn't involve any increment of any pointer.

Two of them aren't even legal code.

Code:

$ gcc -std=c99 -Wall main.c
main.c: In function ‘main’:
main.c:21:10: error: lvalue required as left operand of assignment
   (*p)++ = j;
          ^
main.c:25:10: error: lvalue required as left operand of assignment
   ++(*p) = j;

You can always write code to test ideas you know.

Code:

#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>

void dump ( char *s, int *arr, int *p, int n ) {
  printf("%s results in elements=",s);
  for ( int i = 0 ; i < n ; i++ ) {
    printf("%d ", arr[i]);
  }
  ptrdiff_t pd = p - arr;
  printf("\np is pointing to the %td element\n",pd);
}

int main()
{
  int arr[10] = { 0 };
  int *p = arr;
  int j = 3;
  *(p++) = j;
  dump("*(p++) = j",arr,p,10);
//   (*p)++ = j;
//   dump("",arr,p,10);
  *(++p) = j;
  dump("*(++p) = j",arr,p,10);
//   ++(*p) = j;
//   dump("",arr,p,10);
  return 0;
}

$ gcc -std=c99 -Wall main.c
$ ./a.out 
*(p++) = j results in elements=3 0 0 0 0 0 0 0 0 0 
p is pointing to the 1 element
*(++p) = j results in elements=3 0 3 0 0 0 0 0 0 0 
p is pointing to the 2 element