/*
	Pointer example 3
*/
#include <stdio.h>
#include <stdlib.h>
#define MAX_SIZE 10

void init_array(int size, int a[]) {
    /*  initialize elements[0..size-1] of array a 

	Pre: 0 <= size < number of elements in a
	Post: none
	Side Effects: 
	    elements[0..size-1] of array a satisfy a[i] == i
    */

    int i;
    for (i=0; i < size; i++ ) {
  	a[i] = i;
    }
}

int* copy_array(int size, int a[]) {
    /* 
	create a copy of the segment [0..size-1] of array argument a

	Note the convention of using int a[] in the argument list
	to indicate that the pointer is to an array, not just a 
	single int.

	Pre:  0 < size <= number of elements in a
	      sufficient memory for the copy to be allocated
	Post: copy_array(size, a) points to new array that is a copy
	      of a[0] ... a[size-1]
	Side Effects: an region of memory of sufficient size to hold
	      the copy is allocated.
	Future Conditions: the caller is responsible for freeing the 
	      copy later.
    */

    int* p_copy;
    int i;

    p_copy = (int* ) calloc(size, sizeof(a[0]) );
    
    /* if unable to allocate, a NULL pointer is returned */
    if ( p_copy == NULL ) {
	fprintf(stderr, "copy_array could not allocate sufficient memory.");
	exit(1);
    }

    for ( i=0; i < size; i++ ) {
	p_copy[i] = a[i];
    }

    return p_copy;
}

void main(int argc, char* argv[]) {
    int a[MAX_SIZE];	/* a is an array of MAX_SIZE ints */
    int a_size = sizeof(a) / sizeof(a[0]);  /* of this size */

    int* b;		/* b will point to an array */
    int b_size;		/* of this size */
    int i;

    printf("\nThis is the output from %s:\n\n", argv[0]);

    printf("The address of a is %x\n", (int) a);
    printf("The number of elements in a is %d\n", a_size);
    printf("The size of an element of a is %d bytes\n", (int) sizeof(a[0]) );
    printf("The number of bytes total in a is %d\n", (int) sizeof(a) );

    init_array(a_size, a);
    printf("a contains:");
    for (i=0; i < a_size; i++) {
	printf("%d ", a[i]);
    }
    printf("\n\n");

    b_size = a_size -2;
    b = copy_array(b_size, a);
    printf("The address pointed to by b is %x\n", (int) b);
    printf("b contains:");
    for (i=0; i < b_size; i++) {
	printf("%d ", *(b+i) );
    }
    printf("\n");

}