天道酬勤，每日记点笔记也是蛮有意思的。
今天温习了下 POINTERS ON C 书中的链表一章，记录下使用二级指针对链表进行添加和删除处理。
插入函数：
#define TRUE 1
#define FALSE 0
/*
* brief： Single Linked List
* para: head -> the head of list
* newValue -> item which to be inserted
*/
int sll_insert(node **head,int newValue)
{
node * curr;
node *new;
// find the position
while((curr = *head) != NULL && curry->value <newValue)
head = &curr->next;
// new
new = (node *)malloc(sizeof(node));
if(new == NULL)return FALSE;
//insert
new->value = newValue;
new->next = curr;
*head = new;
return TRUE;
}
删除函数：
typedefbool(* remove_fn)(node const* v);
// 写法一：
void remove_if(node ** head, remove_fn rm)
{
node *curr;
while( (curr = *head) != NULL)
{
// notice entry and curr point both point to the same one
node *entry = curr;//delete it !!
if(rm(entry)){
*head = curr->next;
free(entry);
}else{
head = &curr->next;
}
}
}
不过注意到 写法一 中重复比较多，例如curr 其实都没必要存在！所以我更推荐写法二。
// 写法二：
void remove_if(node ** head, remove_fn rm)
{
for(node** curr = head; *curr; )
{
node * entry = *curr;
if(rm(entry))
{
*curr = entry->next;
free(entry);
}
else
curr = &entry->next;
}
}
