/* An example of

	Creating dynamically an array
	Populating the array
	Displaying the contents
	Freeing up the memory

	Version 4 : Check memory has been assigned
		    Read and Write values using pointers
		    Pass array data to a function


*/

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


int Sum ( int *Data, int n )	/* Define our function 			*/
{
    int Sum = 0,i;		/* Define working variables 		*/

    for ( i = 0 ; i < n ; i++ )
    {
        printf("Item %d=%d\n", i, Data[i]);
        Sum += Data[i];		/* This means   Sum = Sum + Data[i] 	*/
    }


    return Sum;			/* Return the value			*/

}
int main(void)
{
    int *ipArray = NULL;		/* Create the pointer and set   */
    /* to null to start with 	*/

    int *ipStartValue = NULL;	/* A place to store ipArray's   */
    /* initial value ,ie ipArray[0] */
    int iSize = 0;		/* Define our 'size' variable 	*/

    int i;			/* A Loop variables 	        */

    /* Prompt for array size */

    printf("\nHow big is the array to be ? ");
    scanf("%d",&iSize);

    /* Allocate the memory */
    ipArray = (int *)calloc(iSize, sizeof(int));

    if ( ipArray == NULL )
    {
        printf("\nUnable to allocate the memory requested");
        printf("\n  ** Program terminating ** \n");
        exit (1);
    }

    /* Store the base memory address for use later */
    ipStartValue = ipArray;

    /* Populate the array (Method 2 - Use Pointers: This is much faster !) */
    for ( i = 0 ; i < iSize ; i++ )
        ipArray[i] = i;

    /* Display the sum of the values in the array */

    printf("\nThe sum of the array values is %d ",Sum(ipArray,iSize) );

    /* free memory : Again, reset ipArray to its origin */

    ipArray = ipStartValue;
    free(ipArray);

    /* The above two lines could be replaced with    free (ipStartValue)   */

    return 0;
}