Question

Write a menu driven program to implement queue operations

such as Enqueue, Dequeue, Peek, Display of elements, isEmpty,

isFull using dynamic array.

Answer 1

#include <stdio.h>
#include <stdlib.h>
struct Queue
{
	int *items;     
	int maxsize;    
	int front;      
	int rear;       
	int size;       
};
struct Queue* createNewQueue(int size)
{
	struct Queue *queue = NULL;
	queue = (struct Queue*)malloc(sizeof(struct Queue));
	queue->items = (int*)malloc(size * sizeof(int));
	queue->maxsize = size;
	queue->front = 0;
	queue->rear = -1;
	queue->size = 0;
	return queue;
}
int isEmpty(struct Queue *queue) {
	return queue->size==0;
}
int Peek(struct Queue *queue)
{
	if (isEmpty(queue))
	{
		printf("Queue is empty.\n");
	}else{
		return queue->items[queue->front];
	}
}
int isFull (struct Queue *queue) {
	return (queue->size == queue->maxsize);
}


void Enqueue(struct Queue *queue, int x)
{
	if (isFull(queue) == 1)
	{
		printf("Queue is full.\n");
	}else{
		queue->rear = (queue->rear + 1) % queue->maxsize;    
		queue->items[queue->rear] = x;
		queue->size++;
	}
}


void Dequeue(struct Queue *queue)
{
	if (isEmpty(queue))  
	{
		printf("Queue is empty.\n");
	}else{
		queue->front = (queue->front + 1) % queue->maxsize; 
		queue->size--;
	}
	
}
void Display (struct Queue *queue){
	int i;
	if (isEmpty(queue))  
	{
		printf("Queue is empty.\n");
	}else{
		printf("All values: \n");
		for(i = queue->front; i <= queue->rear; i++){
			printf("%d\n", queue->items[i]);
		}
	}
	
		
}


int main()
{
	struct Queue *queue = createNewQueue(5);


	Enqueue(queue, 1);
	Enqueue(queue, 2);
	Enqueue(queue, 3);
	Enqueue(queue, 4);


	Display(queue);


	Dequeue(queue);
	Dequeue(queue);
	Dequeue(queue);
	Dequeue(queue);


	Enqueue(queue, 5);
	Enqueue(queue, 6);


	if (isEmpty(queue)) {
		printf("The Queue is empty");
	}
	else {
		printf("The Queue is not empty");
	}


	getchar();
	getchar();
	return 0;
}