C和指针 十二章 双链表没有实现

这一章主要讲了链表；

单链表和双链表，由于某些原因，只实现了单链表；双链表等我看到后边数据结构再回来补上去

#include <stdio.h>
#include <stdlib.h>
//这段代码参考了c和指针以及深入浅出C语言程序设计链表一部分，但是插入元素的那段代码是深入浅出那里的，比较简单
typedef struct NODE
{
    int value;
    struct NODE *link;
} Node;
Node *head;

//使用数组建立动态链表,先创建头节点，再创建第一个数据节点，并连接到头节点后面，如果再有新数据就再创建节点
Node *creatlist( int *a, int n);
void outputlist( Node *head);//链表输出
void insertlist( Node *head, int x );//插入一个值
void deletelist( Node *head, int new_value );



int main()
{
    int a[10]= { 10, 20, 30, 40, 50 }, i;

    printf("数组初值是 \n");
    for( i = 0; i < 5; i++ )
    {
        printf( "%d\t", a[i]);

    }
    printf("\n");
    head = creatlist( a, 5 );
    printf( "使用数组元素创建的动态链表：\n");
    outputlist( head );
    int x;
    x=25;
    insertlist( head, x );
    deletelist( head, x );
    outputlist( head );
    return 0;
}
Node *creatlist( int *a, int n)
{
    Node *head, *p1, *p2;
    int i;
    head = (Node *) malloc( sizeof( Node ) );
    if( head == NULL)
    {
        printf("没有分配足够内存");
        exit(0);
    }
    p1 = head;
    for( i = 0; i < n; i++ )
    {
        p2 = malloc( sizeof( Node ) );
        if( p2 == NULL)
        {
            printf("没有分配足够内存");
            exit(0);
        }
        p1->link = p2;
        p2->value = a[i];
        p1 = p2;
    }
    p1->link = NULL;
    return head;
}
void outputlist( Node *head)//输出链表
{
    Node *p;
    p = head->link;
    printf("head->");
    while( p != NULL )
    {
        printf("%d->", p->value);
        p = p->link;
    }
    printf("NULL\n");
}

void insertlist( Node *head, int new_value )
{
    Node *current;
    Node *precious;
    Node *news;
    precious = head;
    current = head->link;
    while(  current != NULL )
    {
        if( current->value < new_value )
        {
        precious = current;
        current = current->link;
        }
       else
        break;
    }
    news =(Node *) malloc( sizeof (Node) );
    if (news == NULL)
    {
        printf("出错\n");
        exit(0);
    }
    news->value = new_value;
    news ->link = current;
    precious->link = news;
    outputlist( precious );
}

void deletelist( Node *head, int new_value )
{
    Node *current;
    Node *precious;
    precious = head;
    int flag;
    current = head->link;
    while(  current != NULL )
    {
        if( current->value == new_value )
        {
        flag = 1;
        break;
        }
     precious = current;
     current = current->link;
    }
    if( flag == 1)
    {
            precious->link = current->link;

    }
    outputlist( precious );
}