循环队列实现

#include "stdafx.h"
#include"iostream"
using namespace std;
typedef int QElem;
typedef int Status;
#define MAXSIZE 100
typedef struct {
	QElem *base;
	int front;
	int rear;	
}CirQueue;

//初始化队列
Status InitCirQueue(CirQueue &Q)
{
	Q.base = (QElem*)malloc(MAXSIZE * sizeof(QElem));
	if (!Q.base) exit(OVERFLOW);
	Q.front = Q.rear = 0;
	return true;
}

//队列长度
int QueueLength(CirQueue &Q) {
	return (Q.rear - Q.front + MAXSIZE) % MAXSIZE;	
}

//入队列
Status EnCirQueue(CirQueue &Q,QElem e) {
	if (Q.front == (Q.rear + 1) % MAXSIZE) return false;
	Q.base[Q.rear] = e;
	Q.rear = (Q.rear + 1) % MAXSIZE;
	return true;

}

//出队列
Status DeQueue(CirQueue &Q,QElem &e) {
	if (Q.front==Q.rear) 
		return false;
		e = Q.base[Q.front];
		Q.front = (Q.front + 1) % MAXSIZE;
		return true;

}

int main()
{CirQueue cirQueue;
	InitCirQueue(cirQueue);
	cout<<QueueLength(cirQueue)<<endl;
	for (int i = 1; i < 5;i++) {
		EnCirQueue(cirQueue, i);
	}
	cout << QueueLength(cirQueue) << endl;
	QElem a;
	DeQueue(cirQueue,a);
	cout << QueueLength(cirQueue) << endl;
    return 0;
}