/*
 * To check if an array forms a palindrome or not using a recursive function
 * @author-Karan Narain(karan@iitk.ac.in)
 *
*/
#include <stdio.h>

/*
 * This program uses pointers.For a non-pointer implementation,replace the pointers by array indices 
 * The parameters p and q point to the first and last elements of the array respectively
*/
void palirec(int *p,int *q)
{
	if(p>=q)
	{
		printf("\nThe array forms a palindrome\n");
	}
	else
	{
		if(*p==*q)
		palirec(p+1,q-1);
		else
		printf("\nThe array does not form a palindrome\n");
	}

}
int main()
{
		int A[10],i=0,temp,len,*p=NULL,*q=NULL;

	//len holds the number of elements in array A.It would be equal to the last value of i before the while loop ends or breaks
	while(i<10)
	{
		printf("Enter a positive element(To stop entering,enter a zero)\n");
		scanf("%d",&temp);
		if(temp==0)
		{
			A[i]=temp;
			break;
		}
		else if(temp<0)
		continue;	//continue will take the control back to while(i<10) for a new iteration,i.e. another element will be input
		else
		{
			A[i]=temp;
			i++;
		}
	
	}
	len=i;
	//if no element was entered
	if(len==0)
	printf("The array has no elements\n");
	else
	{
	printf("The array you entered is :\n");
	for(i=0;i<len;i++)
	printf("%d ",A[i]);
	//Make pointer p point to the first element of the array A
	p=&A[0];
	//Make q point to the last entered element of the array A
	q=&A[len-1];
	palirec(p,q);
	}
	return 0;
}