Queue_based_linkedlist.cpp

#include <cstdlib>
#include <iostream>

using namespace std;

struct Node {
	int data;
	struct Node *next;
};

struct Queue {
	struct Node *front;
	struct Node *rear;
};

struct Node *InitNode(int data) {
	struct Node *tmp = (struct Node *)malloc(sizeof(struct Node));
	tmp->data = data;
	tmp->next = NULL;
	return tmp;
}

struct Queue *createQueue(void) {
	struct Queue *tmp = (struct Queue *)malloc(sizeof(struct Queue));
	tmp->front = tmp->rear = NULL;
	return tmp;
}

void enQueue(struct Queue *q, int data) {
	struct Node *tmp = InitNode(data);

	if (q->front == NULL) {
		q->front = q->rear = tmp;
		return;
	}

	q->rear->next = tmp;
	q->rear = tmp;
}

struct Node *deQueue(struct Queue *q) {
	struct Node *tmp = q->front;
	if (tmp != NULL) {
		q->front = tmp->next;
		return tmp;
	}

	return NULL;
}

int main()
{
	struct Queue* q = createQueue();
	enQueue(q, 10);
	enQueue(q, 20);
	deQueue(q);
	deQueue(q);
	enQueue(q, 30);
	enQueue(q, 40);
	enQueue(q, 50);
	struct Node* n = deQueue(q);
	if (n != NULL)
		printf("Dequeued item is %d", n->data);
	return 0;
}