1 #ifndef QUEUE_H_ 2 #define QUEUE_H_ 3  4 #include <stdbool.h> 5 #define QUEUEMAX 10 6  7 typedef int Item; 8  9 typedef struct node10 {11     Item item;12     struct node * next;13 } Node;14 15 typedef struct queue 16 {17     Node * front;18     Node * rear;19     int length;20 } Queue;21 22 void InitializeQueue(Queue * pq);23 24 bool QueueIsEmpty(const Queue * pq);25 26 bool QueueIsFull(const Queue * pq);27 28 int QueueItemCount(const Queue * pq);29 30 bool EnQueue(Item item, Queue * pq);31 32 bool DeQueue(Item * pitem, Queue * pq);33 34 void ShowQueue(const Queue * pq);35 36 void EmptyTheQueue(Queue * pq);37 #endif

#include <stdio.h>#include "queue.h"void eatline(void);int main(void){    Queue line;       Item temp;    InitializeQueue(&line);    printf("<a. add    d. delete    s. show    q. quit>\n");    char ch;    while(‘q‘ != (ch = getchar()))    {        eatline();        if(‘a‘ != ch && ‘d‘ != ch && ‘s‘ != ch)        {            printf("invalid input!\n");            printf("<a. add    d. delete    s. show    q. quit>\n");            continue;        }        if(‘a‘ == ch)        {            if(QueueIsFull(&line))                printf("Queue is full!\n");            else            {                printf("Integer to add: ");                scanf("%d", &temp);                eatline();                int result = EnQueue(temp, &line);                printf("Putting %d into queue <%s>\n", temp, (true == result? "success" : "failed"));            }        }        else if(‘d‘ == ch)        {            if(QueueIsEmpty(&line))                printf("No data to delete!\n");            else            {                int result = DeQueue(&temp, &line);                printf("Remove %d from queue <%s>\n", temp, (true == result ? "success" : "failed"));            }        }        else if(‘s‘ == ch)        {            if(QueueIsEmpty(&line))                printf("No data to show!\n");            else            {                printf("Here is the queue content:\n");                ShowQueue(&line);            }        }        printf("<a. add    d. delete    s. show    q. quit>\n");    }    EmptyTheQueue(&line);    printf("Bye!\n");    return 0;}void eatline(void){    while(‘\n‘ != getchar())        continue;}

#include <stdio.h>#include <stdlib.h>#include "queue.h"static void CopyToNode(Item item, Node * pn);static void CopyToItem(Item * pitem, Node * pn);void InitializeQueue(Queue * pq){    pq->front = pq->rear = NULL;    pq->length = 0;}bool QueueIsEmpty(const Queue * pq){    return pq->length == 0;}bool QueueIsFull(const Queue * pq){    return pq->length == QUEUEMAX;}int QueueItemCount(const Queue * pq){    return pq->length;}bool EnQueue(Item item, Queue * pq){    if(QueueIsFull(pq))        return false;    Node * pn = (Node *)malloc(sizeof(Node));    if(NULL == pn)    {        printf("Unable to allocate memory!\n");        exit(1);    }    CopyToNode(item, pn);    pn->next = NULL;    if(QueueIsEmpty(pq))        pq->front = pn;    else        pq->rear->next = pn;    pq->rear = pn;    pq->length++;    return true;}bool DeQueue(Item * pitem, Queue * pq){    if(QueueIsEmpty(pq))        return false;    Node * pn;    pn = pq->front;    CopyToItem(pitem, pn);    pq->front = pq->front->next;    free(pn);    pq->length--;    if(0 == pq->length)        pq->rear = NULL;    return true;}void ShowQueue(const Queue * pq){    Node * pn = pq->front;    printf("[");    while(NULL != pn)    {        printf("%d  ", pn->item);        pn = pn->next;    }    printf("]\n");}void EmptyTheQueue(Queue * pq){    Item dummy;    while(!QueueIsEmpty(pq))        DeQueue(&dummy, pq);}static void CopyToNode(Item item, Node * pn){    pn->item = item;}static void CopyToItem(Item * pitem, Node * pn){     *pitem = pn->item;}