链队列的初始化，入队，出队，计算队的长度，遍历链队销毁队列

#include "stdio.h"

#include "stdlib.h"

typedef struct node{

int data;

struct node *next;

}*pnode;

typedef struct queue{

pnode front;

pnode rear;

}*pqueue;

//初始化队列

pqueue init(pqueue p)

{

p = (pqueue)malloc(sizeof(struct queue));

p->front = p->rear = NULL;

printf("初始化队列已经成功!\n");

return p;

}

//判断队列是否为空

void empty(pqueue p)

{

if (p->rear==NULL)

printf("队列为空!\n");

else

printf("队列不为空!\n");

}

//入队操作

int enqueue(pqueue p)

{

pnode q;

q = (pnode)malloc(sizeof(struct node));

printf("请输入你想入队的数据:\n");

scanf("%d",&q->data);

if (p->front == p->rear&&p->rear==NULL)

p->front = p->rear = q;

else

{

p->rear->next=q;

p->rear = p->rear->next;

p->rear->next = NULL;

}

return 0;

}

//出队操作

int delqueue(pqueue p)

{

if (p->rear==NULL)

printf("队列为空!\n");

else if ( p->front==p->rear&&p->rear != NULL)

{

printf("出队的数据是%d\n", p->front->data);

p->front = p->rear = NULL;

}

else

{

printf("你要出队的数据是:");

printf("%d\n",p->front->data);

p->front = p->front->next;

}

return 0;

}

//遍历链队

void show(pqueue p)

{

pnode f,r;

f = r = (pnode)malloc(sizeof(struct node));

f= p->front;

r = p->rear;

if (r == NULL)

printf("队列为空!\n");

else

while (f != NULL)

{

printf("%d ",f->data);

f = f->next;

}

printf("\n");

}

//计算链队的长度

void sumqueue(pqueue p)

{

int k = 0;

pnode f, r;

f = r = (pnode)malloc(sizeof(struct node));

f = p->front;

r = p->rear;

if (r == NULL)

printf("队列的长度是:0\n");

else

while(f!= NULL){

k++;

f = f->next;

}

printf("队列的长度是:%d\n",k);

}

//销毁队列

void desqueue(pqueue p)

{

if (p->front == p->rear == NULL)

printf("队列为空");

else if (p->rear == p->front != NULL)

free(p);

else

while (p->front != NULL)

{

free(p->front);

p->front = p->front->next;

}

printf("队列已经销毁!\n");

}

//主函数

int main()

{

pqueue p;

p = NULL;

int n;

do{

printf("***************************\n");

printf("1.初始化队列\n2.判断队列是否为空\n3.入队操作\n4.出队操作\n5.遍历队列中的元素\n6.输出队列的长度\n7.销毁队列\n8.退出程序\n");

printf("***************************\n");

printf("请输入你的选择!\n");

scanf("%d", &n);

switch (n){

case 1:

p=init(p);

break;

case 2:

empty(p);

break;

case 3:

enqueue(p);

break;

case 4:

delqueue(p);

break;

case 5:

show(p);

break;

case 6:

sumqueue(p);

break;

case 7:

desqueue(p);

break;

case 8:

break;

default :

printf("请输入正确的选择!\n");

}

} while (n != 8);

printf("程序已结束拜拜!\n");

return 0;

}