单链表（表头结点）

#include <stdio.h>#include <stdlib.h>#define OK              0#define ERROR          -1#define MALLOC_ERROR   -2typedef int ElementType;       //c语言中没有ElementType这个数据类型，讲数据结构时，用这个来泛指某一种数据类型typedef struct node{ElementType data;          //结点的数据struct node *next;         //结点指针}Node;typedef Node *PNode;           //重命名结点指针类型//头插法创建链表int Create_List_Head(PNode h, ElementType data){if (h == NULL){return ERROR;}PNode node =  (PNode)malloc(sizeof(Node)/sizeof(char));if (node == NULL){return MALLOC_ERROR;}node->data = data;node->next = h->next;h->next = node;return OK;}//尾插法创建链表int Create_List_Tail(PNode h, ElementType data){if (h == NULL){return ERROR;}PNode node = (PNode)malloc(sizeof(Node)/sizeof(char));if (node == NULL){return MALLOC_ERROR;}node->data = data;node->next = NULL;//找最后一个结点PNode temp = h;while (temp->next){temp = temp->next;}temp->next = node;return OK;}//在第pos个结点处插入一个数据int Insert_Node(PNode h, int pos, ElementType data){PNode temp = h;int k = 0;//找pos-1个结点while (temp && k < pos-1){temp = temp->next;k++;}if (temp == NULL)        //越界{printf ("无效的插入点\n");return ERROR;}PNode node = (PNode)malloc(sizeof(Node)/sizeof(char));if (node == NULL){return MALLOC_ERROR;}node->data = data;node->next = temp->next;temp->next = node;return OK;}//在链表中删除第pos个结点int Delete_Node(PNode h, int pos){PNode temp = h;int k = 0;//找到删除的结点前一个结点，就是tempwhile (temp && k < pos-1){temp = temp->next;k++;}if (temp == NULL || temp->next == NULL)        //越界{printf ("删除位置越界\n");return ERROR;}PNode p = temp->next;temp->next = p->next;free(p);p = NULL;return OK;}//链表逆序int Inverse_List(PNode h){//h == NULL    头结点开辟失败，为空//h->next == NULL      空表//h->next->next == NULL    只有一个结点if (h->next == NULL || h->next->next == NULL){return OK;}PNode pre = h->next;PNode cur = pre->next;PNode next = NULL;while(cur){next = cur->next;cur->next = pre;pre = cur;cur = next;}/* h->next->next == NULL;      //两个等于号！！！，将原来的头指针的指针变为尾指针置空h->next = pre;              //将头结点指向现在的第一个结点，重置头结点的nextreturn OK; */h->next->next = NULL;h->next = pre;              //将头结点指向现在的第一个结点，重置头结点的nextreturn OK;}//查找链表中的元素，找到后返回该结点的指针PNode Search(PNode h, ElementType data){if (h == NULL){return NULL;}PNode temp = h->next;while(temp){if (temp->data == data){return temp;}temp = temp->next;}return NULL;}//计算链表的长度int ListLen(PNode h){int len = 0;PNode temp = h->next;while(temp){temp = temp->next;len++;}return len;}//打印void Display(PNode h){if (h == NULL){return;}PNode temp = h->next;       //链表第一个结点指针while (temp){printf ("%4d",temp->data);temp = temp->next;}printf ("\n");}int main(){PNode head_node = (PNode)malloc(sizeof(Node)/sizeof(char));if (head_node == NULL){return MALLOC_ERROR;}head_node->next = NULL;      //空链表int i = 0;for (i = 0; i < 10; i++){/* //头插法创建链表  if (Create_List_Head(head_node,i) != OK)  {  return ERROR;  } *///尾插法创建链表if (Create_List_Tail(head_node,i) != OK){return ERROR;}}/* //在第pos个结点处插入一个数据if (Insert_Node(head_node, 6, 7) != OK){return ERROR;}//在链表中删除第pos个结点if (Delete_Node(head_node,4) != OK){return ERROR;} *///将链表逆序if (Inverse_List(head_node) != OK){return ERROR;}Display(head_node);//查找元素PNode p = Search(head_node, 5);if(p == NULL){printf("无此结点\n");}else{printf("%d\n",p->data);}//计算长度int len = ListLen(head_node);printf("%d\n",len);return 0;}