链表实现队列的基本操作

// linkQueue.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#include <iostream>
using namespace std;
typedef int Element;
typedef struct LinkNode {
	Element date;
	struct LinkNode* next;
}LinkNode;
typedef struct {
	LinkNode* front, * rear;
}LinkQueue;

//================================================带头结点=========================================
//初始化
bool init(LinkQueue &Q) {
	//申请空间
	Q.front = Q.rear = (LinkNode*)malloc(sizeof(LinkNode));
	if (Q.front == NULL || Q.rear == NULL) {
		cout << "初始化失败" << endl;
	}
	Q.front->next = NULL;
	cout << "初始化成功" << endl;
	return true;
}
//判空
bool isEmpty(LinkQueue& Q) {
	if (Q.front == Q.rear) {
		cout << "队列为空" << endl;
		return true;
	}
	cout << "队列不空" << endl;
	return false;
}
//入队
bool insert(LinkQueue& Q, Element e) {
	LinkNode* p = (LinkNode*)malloc(sizeof(LinkNode));
	if (p == NULL) {
		cout << "分配空间失败" << endl;
		return false;
	}
	p->date = e;
	p->next = NULL;
	Q.rear->next = p;
	Q.rear = p;
	cout << "元素" << e << "入队成功" << endl;
	return true;
}
//出队
bool del(LinkQueue& Q, Element e) {
	if (isEmpty(Q)) {
		return false;
	}
	LinkNode* p = Q.front->next;
	e = p->date;
	Q.front->next = p->next;
	//如果front的下一个元素是rear，在删除尾节点后，front 和 rear 的next都指向了空，变为空队列。
	if (Q.rear == p) {
		Q.front = Q.rear;
	}
	free(p);
	cout << "元素" << e << "出队成功" << endl;
	return true;
}
bool show(LinkQueue& Q) {
	if (isEmpty(Q)) {
		return false;
	}
	Element e = 0;
	LinkNode* p = Q.front;
	while (p->next != NULL) {
		cout << p->next->date << endl;
		p = p->next;
	}
	return true;
}
//测试带头结点
void testLinkQueue() {
	LinkQueue Q;
	init(Q);
	isEmpty(Q);
	Element e = 1;
	while (e <= 3) {
		insert(Q, e);
		e++;
	}
	show(Q);
	isEmpty(Q);
	del(Q, e);
	del(Q, e);
	del(Q, e);
	show(Q);
}
//================================================不带头结点=========================================
//初始化
bool init2(LinkQueue& Q) {
	Q.front = Q.rear = (LinkNode*)malloc(sizeof(LinkNode*));
	if (Q.front == NULL || Q.rear == NULL) {
		cout << "初始化失败" << endl;
		return false;
	}
	Q.front = Q.rear = NULL;
	cout << "初始化成功";
	return true;
}
//判空
bool isEmpty2(LinkQueue& Q) {
	if (Q.front == NULL) {
		cout << "队列为空" << endl;
		return true;
	}
	cout << "队列不为空" << endl;
	return false;
}
//入队
bool insert2(LinkQueue& Q, Element e) {
	LinkNode* p = (LinkNode*)malloc(sizeof(LinkNode));
	if (p == NULL) {
		cout << "分配空间失败" << endl;
		return false;
	}
	p->date = e;
	p->next = NULL;
	if (isEmpty2(Q)) {
		Q.front = p;
		Q.rear = p;
	}
	else {
		Q.rear->next = p;
		Q.rear = p;
	}
	cout << "元素" << e << "入队成功" << endl;
	return true;
}
//出队
bool del2(LinkQueue& Q, Element& e) {
	if (isEmpty2(Q)) {
		return false;
	}
	LinkNode* p = (LinkNode*)malloc(sizeof(LinkNode));
	if (p == NULL) {
		cout << "分配空间失败" << endl;
		return false;
	}
	p = Q.front;
	e = p->date;
	Q.front = p->next;
	if (p == Q.rear) {
		Q.front = NULL;
		Q.rear = NULL;
	}
	free(p);
	
	cout << "元素" << e << "出队成功" << endl;
	return true;
}
//展示
bool show2(LinkQueue& Q) {
	if (isEmpty2(Q)) {
		return false;
	}
	LinkNode* p = Q.front;
	while (p != NULL) {
		cout << p->date << endl;
		p = p->next;
	}
	return true;

}
void testLinkQueue2() {
	LinkQueue Q;
	init2(Q);
	isEmpty2(Q);
	Element e = 1;
	while (e <= 3) {
		insert2(Q, e);
		e++;
	}
	show2(Q);
	del2(Q, e);
	del2(Q, e);
	del2(Q, e);
	del2(Q, e);

}

int main()
{
	cout << "===================带头节点==================" <<endl;
	testLinkQueue();
	cout << "===================不带头节点==================" <<endl;
	testLinkQueue2();

}