链表使用

//倒序输出
#include<iostream>
using namespace std;
struct node{
    int data;
    node*next;
};

node*header()
{
    node *head, *n;
    int a;
    head = NULL;
    cout << "首节点插入法产生链表，输入数据（-1结束）：" << endl;

    for (cin >> a; a != -1; cin >> a)
    {
        n = new node;
        n->data = a;
        if (!head)
            head = n, n->next = NULL;
        else 
            n->next = head, head = n;
    }
    return head;
}
int va(node *head)
{
    node *a, *b;
    a = head;
    b = head->next;

    for (; b != NULL; a = a->next, b = b->next)
    {
        if (a->data > b->data)
            return 0;
    }
    return 1;
}

int main()
{
    node *p1;
    p1 = header();
    node *cp = p1;//先弄个副本,p1指针要始终指向人为的head,这样循环完内存都不能回收了已经没有指针指向申请的那段内存了.head始终指向当前节点, 也就是最后申请的一个
    while (cp)
    {
        cout << cp->data << "  ";
        cp = cp->next;
    }
    if (va(p1) == 1)
        cout << "递增单链表元素！" << endl;
    else cout << "非递增单链表元素！" << endl;
    system("pause");
    return 0;
}