写出实现双向链表的建表、销毁表、清空表、判断空、求表长度、按值查找等基本操作的C语言程序代码

双向链表结构体定义：

typedef struct DuLNode {
    ElemType data; // 数据域
    struct DuLNode *prior; // 指向前驱结点
    struct DuLNode *next; // 指向后继结点
} DuLNode, *DuLinkedList;

建表操作：

void CreateList(DuLinkedList *L, int n) {
    *L = (DuLinkedList) malloc(sizeof(DuLNode));
    (*L)->prior = NULL;
    (*L)->next = NULL;

    DuLinkedList p = *L;
    for (int i = 0; i < n; i++) {
        DuLinkedList q = (DuLinkedList) malloc(sizeof(DuLNode));
        scanf("%d", &q->data);
        q->prior = p;
        q->next = p->next;
        p->next = q;
        p = q;
    }
}

销毁表操作：

void DestroyList(DuLinkedList *L) {
    DuLinkedList p = (*L)->next;
    while (p != NULL) {
        DuLinkedList q = p->next;
        free(p);
        p = q;
    }
    (*L)->next = NULL;
}

清空表操作：

void ClearList(DuLinkedList L) {
    DuLinkedList p = L->next;
    while (p != NULL) {
        DuLinkedList q = p->next;
        free(p);
        p = q;
    }
    L->next = NULL;
}

判断空操作：

bool ListIsEmpty(DuLinkedList L) {
    return L->next == NULL;
}

求表长度操作：

int ListLength(DuLinkedList L) {
    int len = 0;
    DuLinkedList p = L->next;
    while (p != NULL) {
        len++;
        p = p->next;
    }
    return len;
}

按值查找操作：

DuLinkedList GetElem(DuLinkedList L, ElemType e) {
    DuLinkedList p = L->next;
    while (p != NULL && p->data != e) {
        p = p->next;
    }
    return p;
}