/*
Programmer:   Greg Perkins
Program:      rotate.c
Class:        CS 73 / UNIX
Due:          April 7, 1998

This program uses pointers to rotate the elements of an array in a
positive/right direction or in a negative/left direction. It also uses
command line arguments during compilation to adjust the array between
'integer', 'character', or 'float' types.
*/

#include <stdio.h>

#ifdef integer
#define message printf("'Compiled for an integer array.'\n")
#define rcout printf(" %d ", *(a + j))
#define arr_type int
#define array {1,2,3,4,5}
#define length 5
#define type_name_string "int"
#endif

#ifdef character
#define message printf("'Compiled for a character array.'\n")
#define rcout printf(" %c ", *(a + j))
#define arr_type char
#define array {'f','l','y','s','w','a','t','t','e','r'}
#define length 10
#define type_name_string "char"
#endif

#ifdef decimal
#define message printf("'Compiled for a float array.'\n")
#define rcout printf(" %f ", *(a + j))
#define arr_type float
#define array {1.11111,2.22222,3.33333,4.44444,5.55555}
#define length 5
#define type_name_string "float"
#endif
 
/************************** FUNCTION PROTOTYPES ****************************/
rotate(arr_type *arr, int arr_len, int rotation);

main()
{
	int direction;
	int j;
	arr_type *a;
	arr_type vec[] = array;
	a = vec;
	
	message;					/* verification of type program compiled for */

	do
	{
		printf("\nEnter the number of spaces to rotate the array elements:\n");
		printf("(Positive - right, Negative - left, 0 to stop)\n");
		scanf("%d", &direction);

		if (direction != 0)
		{
			printf("\nShift %d place(s) or %d place(s):\n",direction,direction%length);
			printf("Orig. array  : ");
				for (j = 0; j < length; j++)
					rcout;
			printf("\n");

			rotate(a, length, direction);

			printf("Rotated array: ");
			for (j = 0; j < length; j++)
				rcout;
			printf("\n");
		}
	}
	while (direction != 0);
}

/************************* FUNCTION DEFINITIONS *****************************/
rotate(arr_type *arr, int arr_len, int rotation)
{
	int j, k;
	int actual_rotation = rotation % arr_len;
	arr_type temp;

	if (actual_rotation < 0)				/* negative or left rotation */
	{
		actual_rotation *= -1;
		for (k = 0; k < actual_rotation; k++)
			for (j = 0, temp = *(arr + j); j < arr_len; j++)
				if (j + 1 == arr_len)
					*(arr + j) = temp;
				else
					*(arr + j) = *(arr + j + 1);
	}
	else											/* positive or right rotation */
		for (k = 0; k < actual_rotation; k++)
			for (j = arr_len - 1, temp = *(arr + j); j >= 0; j--)
				if (j == 0)
					*(arr + j) = temp;
				else
					*(arr + j) = *(arr + (j - 1));
}