链队列

一、定义结构体

#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>
#define OVERFLOW -1
#define OK 1
#define ERROR 0
typedef int Status;
typedef int QElemType;
typedef struct Qnode {
	QElemType data;
	struct Qnode* next;
}QNode,*QueuePtr;

typedef struct {
	QueuePtr front;//队头指针
	QueuePtr rear;//队尾指针
}LinkQueue;
LinkQueue Q;

二、初始化

链队的初始化

Status InitQueue(LinkQueue& Q) {
	Q.front = Q.rear = (QueuePtr)malloc(sizeof(QNode));
	if (!Q.front) exit(OVERFLOW);
	Q.front->next = NULL;
	return OK;
}

三、链队销毁

Status DestoryQueue(LinkQueue & Q) {
	QueuePtr p;
	while (Q.front) {
		p = Q.front->next;
		free(Q.front);
		Q.front = p;
	}
	return OK;
}

四、链队列入队 e元素入队

Status EnQueue(LinkQueue& Q, QElemType e) {
	QueuePtr p = (QueuePtr)malloc(sizeof(QNode));
	//QueuePtr p = new QNode;
	p->data = e;
	if (!p) exit(OVERFLOW);
	p->data = e;
	p->next = NULL;
	Q.rear->next = p;
	Q.rear = p;
	return OK;
}

五、链队出队

Status DeQueue(LinkQueue& Q, QElemType& e) {
	QueuePtr p;
	if (Q.front == Q.rear) return ERROR;
	p = Q.front->next;
	e = p->data;
	Q.front->next = p->next;
	if (Q.rear == p) Q.rear = Q.front;
	free(p);
	return OK;
}

六、取元素

Status GetHead(LinkQueue Q, QElemType& e) {
	if (Q.front == Q.rear) return ERROR;
	e = Q.front->next->data;
}

七、main

int main() {
	InitQueue(Q);
	QElemType e;
	printf("输入入队元素e,输入-1停止\n");
	scanf("%d", &e);
	while (e != -1) {
		EnQueue(Q, e);
		scanf("%d", &e);
	}
	GetHead(Q, e);
	printf("头元素%d\n", e);
	printf("出对\n");
	while (Q.front != Q.rear)
	{
		DeQueue(Q, e);
		printf("%d",e);
	}
}

八、完整代码

#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>
#define OVERFLOW -1
#define OK 1
#define ERROR 0
typedef int Status;
typedef int QElemType;
typedef struct Qnode {
	QElemType data;
	struct Qnode* next;
}QNode,*QueuePtr;

typedef struct {
	QueuePtr front;//队头指针
	QueuePtr rear;//队尾指针
}LinkQueue;
LinkQueue Q;
//链队的初始化
Status InitQueue(LinkQueue& Q) {
	Q.front = Q.rear = (QueuePtr)malloc(sizeof(QNode));
	if (!Q.front) exit(OVERFLOW);
	Q.front->next = NULL;
	return OK;
}
//链队销毁
Status DestoryQueue(LinkQueue & Q) {
	QueuePtr p;
	while (Q.front) {
		p = Q.front->next;
		free(Q.front);
		Q.front = p;
	}
	return OK;
}
//链队列入队 e元素入队
Status EnQueue(LinkQueue& Q, QElemType e) {
	QueuePtr p = (QueuePtr)malloc(sizeof(QNode));
	//QueuePtr p = new QNode;
	p->data = e;
	if (!p) exit(OVERFLOW);
	p->data = e;
	p->next = NULL;
	Q.rear->next = p;
	Q.rear = p;
	return OK;
}
//链队出队
Status DeQueue(LinkQueue& Q, QElemType& e) {
	QueuePtr p;
	if (Q.front == Q.rear) return ERROR;
	p = Q.front->next;
	e = p->data;
	Q.front->next = p->next;
	if (Q.rear == p) Q.rear = Q.front;
	free(p);
	return OK;
}
//对头元素
Status GetHead(LinkQueue Q, QElemType& e) {
	if (Q.front == Q.rear) return ERROR;
	e = Q.front->next->data;
}
int main() {
	InitQueue(Q);
	QElemType e;
	printf("输入入队元素e,输入-1停止\n");
	scanf("%d", &e);
	while (e != -1) {
		EnQueue(Q, e);
		scanf("%d", &e);
	}
	GetHead(Q, e);
	printf("头元素%d\n", e);
	printf("出对\n");
	while (Q.front != Q.rear)
	{
		DeQueue(Q, e);
		printf("%d",e);
	}
}

运行结果：

输入入队元素e,输入-1停止
1
2
3
4
5
-1
头元素1
出对
12345