/* 	Example 18.2 : Filtering an array with a queue
	Removes all negative numbers from an array using queue
	Author: Peter Brusilovsky 
*/

#include "QueueIntAr.h"
#include <stdio.h>
#define N 10 /* dimension of the array */
void readarray(int ar[], int n);
void filter_array(int ar[], int n);
void printarray(int ar[], int n);

main() {
	/* declare an array */
	int testarray[N]; /* elements from ar[0] to ar[N-1]; */
	
	readarray(testarray, N);
	printf("Before filtering, numbers are: ");
	printarray(testarray, N);
	filter_array(testarray, N);
	printf("After filtering, numbers are: ");
	printarray(testarray, N);

	return 0;
}

/* integer array input */
void readarray(int ar[], int n_of_elements) {
	int i;
	for (i = 0; i < n_of_elements; ++i) {
		printf("%d> ", i);
		scanf("%d", &ar[i]);
	}
	return;
}

/* print integer array */
void printarray(int ar[], int n_of_elements) {
	int i;
	for (i = 0; i < n_of_elements; ++i) 
		printf ("%d ", ar[i]);
	printf("\n");
	return;
}

/* filter integer array by removing negative numbers */
void filter_array(int ar[], int n) {
	int i;
	struct intqueue *q;
	
	q = createQueue(N);

	
	for (i = 0; i < n; ++i) 
		if (ar[i] >= 0) 
			enqueue(q, ar[i]);
	
	for (i = 0; i < n;  ++i) 
		if (emptyQueue(q))
			ar[i] = 0;
		else
			dequeue(q, &ar[i]);
		
	destroyQueue(q);
	return;
}