单链表的实现

//链式链表c语言版
typedef int ElemType;
typedef struct Node //链式链表定义
{
    struct Node* next;
    int data;
}ListLink;

ListLink* ListInit()//链式链表初始化
{
    ListLink* head = (Node*)malloc(sizeof(Node));//创建一个头结点
    ListLink* p = head;//声明一个指针指向头结点，用于遍历链表
        for(int i = 1; i < 9; ++i)
        {
            //创建新结点
            ListLink* q = (Node*)malloc(sizeof(ListLink));
            q->data = i;
            q->next = nullptr;
            //继续将尾节点作为p
            p->next = q;
            p = p->next;
        }
        return head;
}

ListLink* ListGet(ListLink* List, ElemType e)//按值查找
{
    ListLink* p = List->next;
    while (p && (p->data)!=e)
    {
        p = p->next;
    }
    return p;
   
}

ListLink* ListGetIndex(ListLink* List, int i)//按位置查找
{
    if (i == 0)
        return List;
    if (i < 1)
        return nullptr;
    int j = 1;
    ListLink* p = List->next;//用一个指针指向第一个结点
    while (p && j < i)
    {
        p = p->next;
        j++;
    }
    return p;
}

ListLink* ListInsert(ListLink* List, int i, ElemType e)//在第i个位置插入元素e
{
    ListLink* temp = List;//创建临时结点List
   //首先找到要插入位置的上一个结点
    int j = 1;
    for (j; j < i; ++j)
    {
        if (!temp)
            return temp;
        temp = temp->next; //进行遍历 temp一步的往后移
    }
   
    ListLink* s = (ListLink*)malloc(sizeof(ListLink));
    s->data = e;
    s->next = temp->next;
    temp->next = s;
    return List;
}

ListLink* ListInsertHead(ListLink* List, ElemType e)//在头部插入一个元素
{
    ListLink* p = List;
    ListLink* q = (ListLink*)malloc(sizeof(ListLink));
    q->data = e;
    q->next = p->next;
    p->next = q;
    return List;
}

ListLink* ListInsertEnd(ListLink* List, ElemType e)//在尾部插入一个元素
{
    ListLink *p, * q;
    p = List;
    while (p->next)
    {
        p = p->next;
    }
    q = (ListLink*)malloc(sizeof(ListLink));
    q->data = e;
    p->next = q;
    q->next = nullptr;
    return List;
}

ListLink* ListDeleteIndex(ListLink* List, int i)//按位置删除元素
{
    ListLink* p = List; // 创建临时结点
    int j = 1;
    while (j < i && p)
    {
        p = p->next;
        ++j;
    }
    if (!p || j > i)//第i个结点不存在
    {
        return nullptr;
    }
    ListLink* q = p->next;
    p->next = q->next;
    free(q);
    return List;
}

bool ListDeleteElem(ListLink* List, ElemType e)//按值删除元素
{
    ListLink* p = List;
    while (p->next)
    {
        p = p->next;
        if (p->data == e)
            return true;
    }
    return false;
}

void ListClear(ListLink* List)//删除顺序链表全部元素
{
    
}

int ListLength(ListLink* List)//获取顺序链表长度
{
    ListLink* p = List;
    int j = 0;
    while (p->next)
    {
        p = p->next;
        ++j;
    }   
    return j;
}

bool ListEmpty(ListLink* List)//顺序链表是否为空
{
    return List->next == nullptr;

}

void ListShow(ListLink* List)//遍历链表的每个元素
{
    ListLink* i = List;
    while (i->next)
    {
        i = i->next;
        cout << i->data << "  ";
    }
    cout << endl;
}

int main() {
   
        ListLink* p = ListInit();
        ListShow(p);
        cout << endl;
        cout << ListLength(p) << endl;
        ListLink* q = ListGet(p, 6);
        cout << q->data << endl;
        q = ListGetIndex(p, 5);
        cout << q->data << endl;
        q = ListInsert(p, 5, 90);
        ListShow(q);
        q = ListDeleteIndex(p, 5);
        ListShow(q);
        cout << ListEmpty(p) << endl;
        q = ListInsertHead(p, 100);
        ListShow(q);
        q = ListInsertEnd(p, 1000);
        ListShow(q);
        cout << ListLength(p) << endl;
    return 0;

}