Programming

static
int *shift_arr(int *arr, const size_t nelems, const int dir)
{
	int *temp=malloc(nelems * sizeof(int) );
	if(temp==NULL)
		return NULL;
	switch (dir)
	{
	    default:
		case '>':
		    memcpy(&temp[1], arr, (nelems -1) * sizeof(int));
		    temp[0]=arr[nelems -1];
			break;
		case '<':
		    memcpy(temp, &arr[1], (nelems -1) * sizeof(int));
		    temp[nelems -1]=arr[0];
			break;
	}
	memcpy(arr, temp, nelems * sizeof(int));
	free(temp);

	return arr;
}

int *shift(int *arr,
          const size_t nelems,
          const size_t cnt,
          const int dir)
{
    int i=0;
    int *result=NULL;
	if(nelems > 1 && cnt > 0 && strchr("><", dir) !=NULL)
	   for(i=0;
	       i<cnt && (result=shift_arr(arr, nelems, dir))!=NULL;
	       i++);

	return result;
}

#include <stdio.h>

#define SZ (sizeof a / sizeof a[0])

void swap(int b[], int *p, int *q, int s)
{
    int i=0;
    while (i < 2) b[i++] = *p++;
    while (i < s) b[i++] = *q++; 
}

void btoa(int a[], int b[], int s)
{
    for (int i=0; i<s; i++)
        a[i]=b[i];
} 

int main()
{
    int a[] = {1,3,5,7,9,11,13};
    int b[SZ];
    int *p = (a+SZ-2);
    int *q = a;
    swap(b,p,q,SZ);
    btoa(a,b,SZ);
}