/*
 * ISA 563, Spring 2011
 * Copyleft by Muhammad Abdulla
 */

#include <stdio.h>

/*
 * ptr_array.c -- Illustrates concepts related to pointer and array relationship in C.
 */

#define NELEMS(x) ((sizeof (x))/(sizeof ((x)[0])))

int main ( int argc, char *argv[] )
{
   int a[3];
   int b[5];
   int *p;
   int i;

   // pointer points to the first element of array
   p = &a[0];

   // initialize arrays
   for ( i = 0; i < NELEMS(a); i++ ) {
      a[i] = 2*i;
   }

   for ( i = 0; i < NELEMS(b); i++ ) {
      b[i] = i*i;
   }

   for ( i = 0; i < NELEMS(a); i++ ) {
      printf("a[%d]: %2d    p[%d]: %d\n", i, a[i], i, p[i]);
   }

   // can easily update pointer value with the address of another array
   p = b;
   for ( i = 0; i < NELEMS(b); i++ ) {
      printf("b[%d]: %2d    p[%d]: %d\n", i, b[i], i, p[i]);
   }

   // Difference 1. Unlike pointers, we cannot assign to an array
   // a = b; // this will cause compilation error

   // Difference 2. sizeof(array) gives the total size of the array, sizeof(pointer) gives
   // gives the size of the pointer object itself, regardless of where its pointing to 
   printf("sizeof(a): %d, sizeof(b): %d, sizeof(p): %d\n", sizeof(a), sizeof(b), sizeof(p)); 

   return 0;
}