问题描述

c语言链表代码求大神解释

insert中的 while( next_node && new_node->data > next_node->data) 是什么意思？
还有excise是什么意思，干什么用的？
最近在学链表，学不清楚...
#include
#include

#include "list.h"

/*
Create a new node containing the specified data,
and return a pointer to this newly-created node.
*/
Lnode * makeNode( int data )
{
Lnode *new_node =(Lnode *)malloc( sizeof( Lnode ));
if( new_node == NULL ) {
fprintf(stderr,"Error: memory allocation failed.n");
exit( 1 );
}
new_node->data = data;
new_node->next = NULL;
return( new_node );
}

/*
Search through list to find the first node with the
specified data, and return a pointer to this node.
If no such node exists, return NULL.
*/
Lnode * findNode( int data, Lnode *head )
{
Lnode *node = head; // start at first node in list

// keep searching until data found, or end of list
while(( node != NULL )&&( node->data != data )) {
node = node->next;
}
return( node );
}

/*
Push new node to front of list and
return the resulting (longer) list
*/
Lnode * push( Lnode *new_node, Lnode *head )
{
new_node->next = head;
return( new_node );
}

/*
Pop first item from list and
return the remaining (shorter) list
*/
Lnode * pop( Lnode *head )
{
Lnode *tmp;

if( head != NULL ) {
    tmp  = head;
    head = head->next;
    free( tmp );
}
return( head );

}

/*
Print all items in the list one by one
*/
void printList( Lnode *head )
{
Lnode *node = head;

// traverse the list printing each node in turn
while( node != NULL ) {
printf( "->%c", node->data );
node = node->next;
}
printf( "n" );
}

/*
Delete all the items from a linked list.
*/
void freeList( Lnode *head )
{
Lnode *node = head;
Lnode *tmp;

while( node != NULL ) {
tmp = node;
node = node->next;
free( tmp );
}
}

Lnode * insert( Lnode *new_node, Lnode *head )
{
Lnode *next_node = head, *prev_node = NULL;
while( next_node && new_node->data > next_node->data) {
prev_node = next_node;
next_node = next_node->next; // find correct position
}
if( prev_node == NULL )
head = new_node;
else {
prev_node->next = new_node; // link new node into list
}
new_node->next = next_node;
return( head );
}

Lnode * excise( Lnode *node, Lnode *head )
{
if( node != NULL ) {
if( node == head )
head = head->next; // remove first item
else {
Lnode *prev_node = head;
while( prev_node && prev_node->next != node ) {
prev_node = prev_node->next;
}
if( prev_node != NULL ) { // node found in list
prev_node->next = node->next;
}
}
}
return( head );
}

解决方案

while( next_node && new_node->data > next_node->data)
当下个节点存在，且新节点的数据大于下个节点的数据时进行循环
excise看逻辑是从head中删除node的，然后返回删除后的链表

解决方案二：

其实这些代码的英文意思就代表了中文执行的含义，

新节点存在，且数据大于下一个节点的数值

删除头结点并返回 搜索通过列表找到第一个节点

指定的数据，并返回一个指向该节点的指针。

如果不存在这样的节点，返回空。 excise就是删除切去的意思

解决方案三：

链表无非就是增删查改，想不清楚的地方自己画一画过程，这样更容易理解

解决方案四：

学习建议先从简单的入手，搞清楚以后再整些复杂的，或者找个带注释的