如何使用指针算法为结构内的数组赋值？

Question

 typedef struct TILE{
 char p[4];
 char ladder,snake;
 char end;
 int boardLoc;
 struct TILE *pointer;
 }tile;

tile *myTable = (tile*) calloc(row*col,sizeof(tile));

//This code works (using brackets [])
(myTable+90)->p[0] = 'a';
(myTable+90)->p[1] = 'b';
(myTable+90)->p[2] = 'c';
(myTable+90)->p[3] = 'd';

//This code does not work (using pointer arithmetic)
*(myTable+90).(*(p+0)) = 'a';
*(myTable+90).(*(p+1)) = 'b';
*(myTable+90).(*(p+2)) = 'c';
*(myTable+90).(*(p+3)) = 'd';

//This code does not work either (arrow operator and pointer arithmetic to access array)
(myTable+90)->(*(p+0)) = 'a';
(myTable+90)->(*(p+1)) = 'b';
(myTable+90)->(*(p+2)) = 'c';
(myTable+90)->(*(p+3)) = 'd';

We are required to use pointer arithmetic in writing our code. I am having a hard time figuring out how to assign a value to an array which is wrapped inside a structure with just utilizing pointer arithmetic method. Is there another way to go through this? Thanks!

Answer 1

The following are all equivalent:

myTable[90].p[3] = 'd';
*(myTable[90].p+3) = 'd';
(myTable+90)->p[3] = 'd';
*((myTable+90)->p+3) = 'd';
(*(myTable+90)).p[3] = 'd';
*((*(myTable+90)).p+3) = 'd';

The first form uses only the array indexing operator [] . The last form uses only pointer addition and dereferences.