源码

/**
  * 创建时间 : 2022/5/21 20:16
  * 作   者 : Marson
  * 内   容 : 队列的链式存储结构(带头结点)
  */


#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>

typedef int ElemType;

//队列结点
typedef struct QNode {
    ElemType data;
    struct QNode *next;
}QNode, QueuePtr;

//队列
typedef struct {
    QueuePtr *front;
    QueuePtr *rear;
}LinkQueue;


/**
 * 初始化
 * 带头结点，front指向头结点，rear指向队列最后一个元素
 *
*/
bool InitQueue(LinkQueue *Q) {
    QueuePtr *s = (QueuePtr *) malloc(sizeof(QueuePtr));
    Q->front = Q->rear = s;
    Q->rear->next = NULL;
    return true;
}


/**
* 入队
*/
bool EnQueue(LinkQueue *Q, ElemType e) {
    QueuePtr *p = (QueuePtr *) malloc(sizeof(QueuePtr));
    p->data = e;
    p->next = NULL;
    Q->rear->next = p;
    Q->rear = p;
    return true;
}


/**
* 出队
*/
bool DeQueue(LinkQueue *Q, ElemType *e) {
    if(Q->front == Q->rear) return false;
    QueuePtr *p = Q->front->next;
    *e = p->data;
    Q->front->next = p->next;

    if (Q->rear == p) Q->front = Q->rear;    // 最后一个元素

    free(p);
    return true;
}


/**
* 取队头元素
*/
bool GetTop(LinkQueue *Q, ElemType *e) {
    if (Q->front == Q->rear) return false;
    else {
        *e = Q->front->next->data;
        return true;
    }
}


/**
* 打印队列
*/
void PrintQueue(LinkQueue *Q) {
    QueuePtr *p = Q->front->next;
    while (p != NULL) {
        printf("%d\n", p->data);
        p = p->next;
    }
}


/**
* 求队列长度
*/
int GetLength(LinkQueue *Q) {
    if (Q->front == Q->rear) return 0;

    int len = 0;
    QueuePtr *p = Q->front->next;
    while (p != NULL) {
        len++;
        p = p->next;
    }
    return len;
}

int main() {
    LinkQueue *Q;
    LinkQueue q;
    Q = &q;
    InitQueue(Q);

    ElemType e;
    int chooseNumber;
    bool ans;

    while (1) {
        printf("******************************\n");
        printf("请操作：\n");
        printf("1.入队\n");
        printf("2.出队\n");
        printf("3.取队头元素\n");
        printf("4.获取队列长度\n");
        printf("5.输出队列\n");
        printf("0(exit):退出程序\n");
        printf("******************************\n");


        scanf("%d", &chooseNumber);

        switch (chooseNumber) {
            case 0:
                exit(0);
                break;
            case 1:
                printf("请输入入队元素：\n");
                scanf("%d", &e);
                ans = EnQueue(Q, e);
                if (ans) printf("入队成功！\n");
                else printf("入队失败！\n");
                break;
            case 2:
                ans = DeQueue(Q, &e);
                if (ans) printf("出队成功！出队元素为%d\n", e);
                else printf("出队失败！\n");
                break;
            case 3:
                ans = GetTop(Q, &e);
                if (ans) printf("队头元素为%d\n", e);
                else printf("队列为空！\n");
                break;
            case 4:
                printf("当前队列长度为%d\n", GetLength(Q));
                break;
            case 5:
                PrintQueue(Q);
                break;
            default:
                printf("输入错误，请重新输入：\n");
                break;
        }
    }
    return 0;
}