Queue_Circular_Array

#include <stdio.h>
#include <stdlib.h>

#define MAX 20

typedef <Element's type> El_type;
typedef struct Queue
{
El_type el[MAX];
int front;
int rear;
} Queue;

/* Initialize Queue */
Eltype *initQ(Queue *q)
{
q = (Queue *)malloc(sizeof(Queue));
if(q!= NULL) 
{
  q->front = -1;
  q->rear = -1;
}
return q;
}

/* Check if a queue is empty */
int empty_queue(queue q)
{
return q.front==-1;
}

/* Check if a queue is full */
int full_queue(queue q)
{
return (q.rear-q.front+1)%maxlength==0;
}

/* Add a new element */
void enqueue(elementtype x,queue *q)
{
if(!full_queue(*q))
{
if(empty_queue(*q))q->front=0;
q->rear=(q->rear+1)%maxlength;
q->data[q->rear]=x;    
}
else printf("Full!");
}

/* Delete an element */
void dequeue(queue *q)
{
if(!empty_queue(*q))
{
if(q->front==q->rear)makenull_queue(q);
else q->front=(q->front+1)%maxlength;
}
else printf("Empty!");
}