单向链表
单链表有一个头节点head，指向链表在内存的首地址。链表中的每一个节点的数据类型为结构体类型，节点有两个成员：整型成员（实际需要保存的数据）和指向下一个结构体类型节点的指针即下一个节点的地址（事实上，此单链表是用于存放整型数据的动态数组）。链表按此结构对各节点的访问需从链表的头找起，后续节点的地址由当前节点给出。无论在表中访问那一个节点，都需要从链表的头开始，顺序向后查找。链表的尾节点由于无后续节点，其指针域为空，写作为NULL。
<a href="http://www.emacsvi.com/wp-content/uploads/2015/10/linkedlist.bmp"><img src="http://www.emacsvi.com/wp-content/uploads/2015/10/linkedlist.bmp" alt="linkedlist" width="600" height="130" class="alignnone size-full wp-image-274" /></a>
<pre lang="c" escaped="true">
/* linkedlist.h */
#ifndef LINKEDLIST_H#define LINKEDLIST_Htypedef struct node *link;
struct node{ unsigned char elem; link next;};link make_node(unsigned char elem);
void free_node(link p);link search(unsigned char elem);void insert(link p);void delete(link p);void traverse(void (*visit)(link));void destroy(void);void push(link p);link pop(void);#endif
</pre>
<pre lang="c" escaped="true">#include <stdlib.h>
#include "linkedlist.h"static link head=NULL;
link make_node(unsigned char elem)
{ link p = malloc(sizeof(*p)); p->elem = elem; p->next = NULL; return p;}void free_node(link p)
{ free(p);}link search(unsigned char elem)
{ link p; for (p = head; p; p = p->next) if (elem == p->elem) return p; return NULL;}void insert(link p)
{ p->next = head; head = p;}void delete(link p)
{ link pre; if (head == p) { head = p->next; return; } for (pre = head; pre; pre = pre->next) if (pre->next == p) { pre->next = p->next; return; }}/* 没有看太明白
void delete(link p){ link *pnext; for (pnext = &head; *pnext; pnext = &(*pnext)->next) if (*pnext == p) { *pnext = p->next; return; }}*/void traverse(void (*visit)(link))
{ link p; for (p = head; p; p = p->next) visit(p);}void destroy(void)
{ link q, p=head; head = NULL; while (p) { q = p; p = p->next; free_node(q); }}void push(link p)
{ insert(p);}link pop(void)
{ if (NULL == head) return NULL; else { link p = head; head = head->next; return p; }}</pre>
<pre lang="c" escaped="true">#include <stdio.h>
#include "linkedlist.h"void print_elem(link p)
{ printf("%d\n", p->elem);}int main(void)
{ link p;insert(make_node(10));
insert(make_node(5)); insert(make_node(90)); p = search(5); delete(p); free_node(p); traverse(print_elem); destroy(); push(make_node(100)); push(make_node(200)); push(make_node(250)); while (p = pop()) { print_elem(p); free_node(p); }return 0;
}</pre>