单向加头链表的[构建、插入、删除、查找、输出]

#include <stdio.h>
#include <malloc.h>
typedef struct lianbiao *ptr;
struct lianbiao
{
    int data;
    ptr next;
};

int main(void)
{
    ptr create();
    void out(ptr p);
    ptr search(ptr p, int x);
    ptr del(ptr h, int x);
    ptr add(ptr head, int x);
    int delEl, searchEl, addEl, delResult, searchResult;

    ptr l = create(); //构建初始链表

    printf("初始链表为:"); //输出初始链表
    out(l);
    printf("\n");

    //查找元素
    printf("输入待查找元素:");
    scanf("%d", &searchEl);

    searchResult = search(l, searchEl);
    if (searchResult)
    {
        searchResult = search(l, searchEl)->data;
        printf("元素%d查找成功\n", searchResult);
    }

    else
        printf("待查找元素不存在！\n");
    printf("\n");

    //删除元素
    printf("输入待删除元素:");
    scanf("%d", &delEl);
    delResult = del(l, delEl);
    if (delResult)
        printf("删除成功！\n");
    else
        printf("待删除元素不存在！\n");
    printf("\n");

    //插入元素
    printf("输入待插入元素:");
    scanf("%d", &addEl);
    add(l, addEl);
}

ptr create() // 构建链表
{
    ptr p, head, last;
    int x;
    //创建头结点
    head = (ptr)malloc(sizeof(ptr));
    head->data = 0;
    last = head;
    last->next = NULL;

    //添加链表元素
    printf("构建初始链表(输入0以结束):");
    scanf("%d", &x);
    while (x != 0)
    {
        p = (ptr)malloc(sizeof(ptr));
        p->data = x;

        //把新元素插入链表
        if (x > last->data) //待插入元素大于所有节点
        {
            last->next = p;
            p->next = NULL;
            last = p;
        }
        else if (x < head->next->data) //待插入元素小于所有节点
        {
            p->next = head->next;
            head->next = p;
        }
        else //一般情况
        {
            ptr f = head, s = f->next;
            while (x > s->data)
            {
                f = s;
                s = s->next;
            }
            p->next = s;
            f->next = p;
        }

        scanf("%d", &x);
    }
    return head;
}

void out(ptr p) //输出链表
{
    p = p->next;
    while (p != NULL)
    {
        printf("%5d", p->data);
        p = p->next;
    }
    printf("\n");
};

ptr search(ptr p, int x) //搜索元素
{
    while (p != NULL)
    {
        if (p->data == x)
            return p;
        p = p->next;
    }
    return 0;
}

ptr del(ptr h, int x) //删除元素
{
    ptr f, s;
    f = h;
    s = h->next;
    while (s->data != x)
    {
        f = s;
        s = s->next;
        if (s->next == NULL)
            break;
    }

    if (s->data == x)
    {
        f->next = s->next;
        free(s);
        return 1;
    }
    else
        return 0;
}

ptr add(ptr head, int x)
{
    ptr p, last, yyy;
    yyy = head;
    while (yyy->next != NULL)
        yyy = yyy->next;
    last = yyy;
    last->next = NULL;

    p = (ptr)malloc(sizeof(ptr));
    p->data = x;

    //把新元素插入链表
    if (x > last->data) //待插入元素大于所有节点
    {
        last->next = p;
        p->next = NULL;
        last = p;
    }
    else if (x < head->next->data) //待插入元素小于所有节点
    {
        p->next = head->next;
        head->next = p;
    }
    else //一般情况
    {
        ptr f = head, s = f->next;
        while (x > s->data)
        {
            f = s;
            s = s->next;
        }
        p->next = s;
        f->next = p;
    }

    printf("添加完成！\n现在的链表为:");
    out(head);
    printf("\n");
}