C和指针笔记——链表的研究和改善

//code by zzlpp && code for link_list training
typedef struct Node
{
    int value;
    struct Node *link;
}Node;

//头文件只包含节点的声明 文

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include "node.h"

Node*creatnode(int value);
void insertnode( Node **pointer,int value );

void main()
{
    Node *p=creatnode(5);
    Node **pointer=&p;
    insertnode(pointer,3);
    do
    {
        printf("%d	",p->value);
        p=p->link;
    }while( p!=NULL );
    printf("
");
    system("pause");
}
Node *creatnode(int value)
{
    Node *root;
    root=( Node *)malloc( sizeof(Node) );
    if (root==NULL)
    {
        free( root );
        printf("error
");
        exit(EXIT_FAILURE);
    }
    root->value=value;
    root->link=NULL;
    return root;
}
void insertnode( Node **pointer,int value )
{
    Node *current;
    Node *previous;

    previous=NULL;
    current=*pointer;

    Node *newnode=( Node* )malloc( sizeof(Node) );
    if ( newnode==NULL )
    {
        free( newnode );
        printf("error
");
        exit(EXIT_FAILURE);
    }
    newnode->value=value;
    while ( current->value<value && current->link!=NULL )
    {
        previous=current;
        current=current->link;
    }
    if ( current->link==NULL )
    {
        if ( current->value<value )
        {
            current->link=newnode;
            newnode->link=NULL;
        }
        else
        {
            newnode->link=current;
            *pointer=newnode;
        }
    }
    else
    {
        newnode->link=current;
        previous->link=newnode;
    }
}

和原书上写的有些出入，总的来说就是要考虑到3种情况，第一种是要考虑插在链表的中间，第二种是要考虑到查到结尾，最后是要你考虑到查到开头，这三种情况缺一不可，个人觉得如此处理更为清晰一些。

件名  “node.h”