链式队列

         //------------------------------队列----------------------------------------//
//队列与栈相反，是一种先进先出(FIFO)的线性表。它只允许在表的一端进行插入，而在另一端删除元素
//允许插入的一端叫做队尾(rear)，允许删除的一端叫做队头(front)
//给链队列增加一个头结点，并令头指针指向头结点。空的链队列的判决条件：头指针和尾指针均指向头结点
//链队列的操作即为单链表的插入和删除操作的特殊情况

//-----------------------------------------------------------------------------//

function.h

#define Status int#define OVERFLOW -2#define TRUE 1#define FALSE 0#define OK 1#define ERROR 0typedef int QElemType;typedef struct QNode{        QElemType data;        struct QNode *next;}QNode, *QueuePtr;typedef struct{       QueuePtr front;       QueuePtr rear;}LinkQueue;void visit_print(QueuePtr p);Status InitQueue(LinkQueue *Q);   //构造Status DestroyQueue(LinkQueue *Q);   //销毁Status ClearQueue(LinkQueue *Q);     //清空Status QueueEmpty(LinkQueue Q); // 为空返回TRUE，否则返回FALSEStatus QueueLength(LinkQueue Q);//返回队列长度Status GetHead(LinkQueue Q, QElemType *e);   // 返回队列的头元素Status EnQueue(LinkQueue *Q, QElemType e);   //插入元素e为新的队尾元素Status DeQueue(LinkQueue *Q, QElemType *e);//若队列不为空返回队头元素，否则返回ERRORStatus QueueTraverse(LinkQueue Q,  void (*visit)(QueuePtr) );//从队头到队尾的队列中每个元素调用函数visit(),一旦失败则操作失败

function.c

#include "function.h"#include <stdio.h>#include <stdlib.h>void visit_print(QueuePtr p){        printf("%d    ", p->data);}Status QueueEmpty(LinkQueue Q){        if( Q.front == Q.rear)        {                printf("the queue is empty!\n");                return OK;        }        else                 return ERROR;}Status InitQueue(LinkQueue *Q){        Q->front = Q->rear = (QueuePtr ) malloc ( sizeof ( QNode ) );//生成一个头结点，数据域为空        if( !Q->front )          exit(OVERFLOW);  //分配失败        Q->front->next=NULL;        return OK;}Status EnQueue(LinkQueue *Q, QElemType e){        QueuePtr p;        p=(QueuePtr ) malloc (sizeof (QNode ));        p->data = e;        p->next = NULL;        Q->rear->next = p;        Q->rear = p;//尾指针后移        return OK;}Status DeQueue(LinkQueue *Q, QElemType *e){        if( Q->front == Q->rear)          return ERROR;        QueuePtr p= (QueuePtr ) malloc (sizeof (QNode ));        p = Q->front->next;        *e = p->data;        Q->front->next = p->next;//头指针后移        if( Q->rear == p)        Q->rear = Q->front;        free(p);        return OK;}Status DestroyQueue(LinkQueue *Q){       QueuePtr p= Q->front = Q->rear;       free(p);       return OK;}Status ClearQueue(LinkQueue *Q){        QElemType *e=(QElemType *)malloc(sizeof(QElemType));      while( Q->front != Q->rear)      {              DeQueue( Q,  e);      }      return OK;}int  QueueLength(LinkQueue Q){        int length=0;        while(Q.front != Q.rear)        {              Q.front = Q.front->next;              length++;        }        return length;}Status GetHead(LinkQueue Q, QElemType *e){        if( Q.front == Q.rear)          return ERROR;        *e = Q.front->next->data;        return OK;}Status QueueTraverse(LinkQueue Q, void (*visit)(QueuePtr)){        if( Q.front == Q.rear)          return ERROR;        QNode *p;        for( p= Q.front->next;p; p= p->next)        {                visit(p);        }        printf("\n");        return OK;}

main.c

//------------------------------队列----------------------------------------////队列与栈相反，是一种先进先出(FIFO)的线性表。它只允许在表的一端进行插入，而在另一端删除元素//允许插入的一端叫做队尾(rear)，允许删除的一端叫做队头(front)//给链队列增加一个头结点，并令头指针指向头结点。空的链队列的判决条件：头指针和尾指针均指向头结点//链队列的操作即为单链表的插入和删除操作的特殊情况//-----------------------------------------------------------------------------//#include <stdio.h>#include <stdlib.h>#include "function.h"int main(void){        LinkQueue Q;        QElemType e;        int i;        InitQueue(&Q);        QueueEmpty(Q);       for(i=0;i<5;i++)        {                scanf("%d", &e);                EnQueue(&Q, e);        }        printf("the queue are:");        QueueTraverse(Q, visit_print);        printf("the queue's length is %d \n", QueueLength(Q));        GetHead(Q ,&e);        printf("the head member of queue is %d\n ", e);        DeQueue(&Q, &e);        printf("delete the head member in queue is %d\n", e);        printf("after delete the head node ,queue are:");        QueueTraverse(Q, visit_print);        printf("the queue length is %d\n", QueueLength(Q));        ClearQueue(&Q);         QueueEmpty(Q);        return 0;}

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