C语言单链表实现方法详解

#ifndef __SLIST_H__#define __SLIST_H__#include<cstdio>#include<malloc.h>#include<assert.h>typedef int ElemType;typedef struct Node { //定义单链表中的结点信息  ElemType data; //结点的数据域  struct Node *next; //结点的指针域}Node,*PNode;typedef struct List { //定义单链表的链表信息  PNode first; //first指向单链表中的第一个结点  PNode last; //last指向单链表中的最后一个结点  size_t size; //记录单链表中的结点个数}List;void InitList(List *list);//初始化单链表void push_back(List *list, ElemType x);//在单链表的末尾插入元素void push_front(List *list, ElemType x);//在单链表的头部插入元素void show_list(List *list);//打印单链表void pop_back(List *list);//删除单链表的最后一个元素void pop_front(List *list);//删除单链表的第一个元素void insert_val(List *list, ElemType val);//将数据元素插入到单链表中（要求此时单链表中的数据元素顺序排列）Node* find(List *list, ElemType x);//查找单链表中数据值为x的结点int length(List *list);//求单链表的长度void delete_val(List *list, ElemType x);//按值删除单链表中的某个数据元素void sort(List *list);//对单链表进行排序void reverse(List *list);//逆置单链表void clear(List *list);//清除单链表void destroy(List *list);//摧毁单链表#endif //__SLIST_H__

#include"slist.h"void InitList(List *list) {  list->first = list->last = (Node*)malloc(sizeof(Node)); //头结点  assert(list->first != NULL);  list->first->next = NULL;  list->size = 0;}void push_back(List *list, ElemType x) {  //step 1：创建一个新的结点  Node *s = (Node*)malloc(sizeof(Node));  assert(s != NULL);  s->data = x;  s->next = NULL;  //step 2：将新结点插入单链表的表尾  list->last->next = s;  list->last = s;  //step 3：更新单链表的长度  list->size++;}void push_front(List *list, ElemType x) {  //step 1：创建一个新的结点  Node *s = (Node*)malloc(sizeof(Node));  assert(s != NULL);  s->data = x;  s->next = NULL;  //step 2：将新结点插入单链表的表头  s->next = list->first->next;  list->first->next = s;  //step 3：判断插入的结点是否是单链表的第一个结点，若是更新链表的尾指针  if (list->size == 0)    list->last = s;  //step 4：更新单链表的长度  list->size++;}void show_list(List *list) {  //step 1：指针p指向单链表的第一个结点  Node *p = list->first->next;  //step 2：循环打印结点的信息  while (p != NULL) {    printf("%d->", p->data);    p = p->next;  }  printf("Nul./n");}void pop_back(List *list) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：定义指针p使其指向目标结点的前一个结点  Node *p = list->first;//从头结点开始  while (p->next != list->last)    p = p->next;  //step 3：删除目标结点  free(list->last);  list->last = p;  list->last->next = NULL;  //step 4：更新单链表的长度  list->size--;}void pop_front(List *list) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：定义指针p使其指向目标结点的前一个结点  Node *p = list->first->next;  //step 3：删除目标结点  list->first->next = p->next;  free(p);  //step 4：判断删除的结点是否是单链表的最后一个结点，若是则更新单链表的尾指针  if (list->size == 1)    list->last = list->first;  //step 4：更新单链表的长度  list->size--;}void insert_val(List *list, ElemType x) {  //step 1：创建一个新的结点  Node *s = (Node*)malloc(sizeof(Node));  assert(s != NULL);  s->data = x;  s->next = NULL;  //step 2：定义指针p使其指向待插入位置的前一个结点  Node *p = list->first;//从头结点开始  while (p->next != NULL && p->next->data < s->data)    p = p->next;  //step 3：判断结点的待插入位置是否是表尾，若是则更新单链表的尾指针  if (p->next == NULL)    list->last = s;  //step 4：插入结点  s->next = p->next;  p->next = s;  //step 5：更新单链表长度  list->size++;}Node* find(List *list, ElemType x) {  //step 1：指针p指向单链表的第一个结点  Node *p = list->first->next;  //step 2：按照循环顺序查找链表结点  while (p != NULL && p->data != x)    p = p->next;  return p;}int length(List *list) {  return list->size;}void delete_val(List *list, ElemType x) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：确定结点在单链表中的位置，并判断其是否存在于单链表中  Node *p = find(list, x);  if (p == NULL) {    printf("要删除的数据不存在！/n");    return;  }  //step 3：判断结点位置是否是表尾  if (p == list->last)//是表尾    pop_back(list);  else {//不是表尾    Node *q = p->next;    p->data = q->data;    p->next = q->next;    free(q);    list->size--;  }}void sort(List *list) {  //step 1：判断单链表中的结点数是否为0或1  if (list->size == 0 || list->size == 1) return;  //step 2：将单链表中第一个结点之后的链表部分截出，方便重新按顺序插入链表之中  Node *s = list->first->next; // 指针s指向单链表的第一个节点  Node *p = s->next;//q指向s后面的结点  list->last = s;//单链表的尾指针指向单链表的第一个结点  list->last->next = NULL;//截断链表  //step 3：将截出的链表中的结点根据其数据域大小重新插入到原来链表中  while (p != NULL) {    s = p;    p = p->next;    Node *q = list->first;    while (q->next != NULL && q->next->data < s->data)      q = q->next;    if (q->next == NULL)//判断q此时指向的是否是单链表的最后一个结点，若是则更新链表的尾指针      list->last = s;    //将结点重新插入链表    s->next = q->next;    q->next = s;  }}void reverse(List *list) {  //step 1：判断单链表中的结点数是否为0或1  if (list->size == 0 || list->size == 1) return;  //step 2：将单链表中第一个结点之后的链表部分截出，然后将截出的链表中的结点按头插法重新插入到原链表中  Node *p = list->first->next;  Node *q = p->next;  list->last = p;  list->last->next = NULL;  while (q != NULL) {    p = q;    q = q->next;    p->next = list->first->next;    list->first->next = p;  }}void clear(List *list) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：释放单链表中的每一个结点  Node *p = list->first->next;  while (p != NULL) {    list->first->next = p->next;    free(p);    p = list->first->next;  }  //step 3：头指针和尾指针重新都指向头结点  list->last = list->first;  //step 4：更新链表长度  list->size = 0;}void destroy(List *list) {  //step 1：清空单链表  clear(list);  //step 2：释放头结点  free(list->first);  //step 3：头指针和尾指针都赋值为空  list->first = list->last = NULL;}

#include"slist.h"void main() {  List mylist;  InitList(&mylist);  ElemType item;  Node *p = NULL;  int select = 1;  while (select) {    printf("*******************************************/n");    printf("*[1] push_back    [2] push_front  */n");    printf("*[3] show_list    [4] pop_back   */n");    printf("*[5] pop_front    [6] insert_val  */n");    printf("*[7] find       [8] length    */n");    printf("*[9] delete_val    [10] sort     */n");    printf("*[11] reverse     [12] clear     */n");    printf("*[13*] destroy     [0] quit_system  */n");    printf("*******************************************/n");    printf("请选择：>>");    scanf("%d", &select);    if (select == 0) break;    switch (select) {    case 1:      printf("请输入要插入的数据（-1结束）:>");      while (scanf("%d", &item), item != -1) {        push_back(&mylist, item);      }      break;    case 2:      printf("请输入要插入的数据（-1结束）:>");      while (scanf("%d", &item), item != -1) {        push_front(&mylist, item);      }      break;    case 3:      show_list(&mylist);      break;    case 4:      pop_back(&mylist);      break;    case 5:      pop_front(&mylist);      break;    case 6:      printf("请输入要插入的数据:>");      scanf("%d", &item);      insert_val(&mylist, item);      break;    case 7:      printf("请输入要查找的数据:>");      scanf("%d", &item);      p = find(&mylist, item);      if (p == NULL)        printf("要查找的数据在单链表中不存在！/n");      break;    case 8:      printf("单链表的长度为%d/n", length(&mylist));      break;    case 9:      printf("请输入要删除的值:>");      scanf("%d", &item);      delete_val(&mylist, item);      break;    case 10:      sort(&mylist);      break;    case 11:      reverse(&mylist);      break;    case 12:      clear(&mylist);      break;      //case 13:      //destroy(&mylist);      //break;    default:      printf("选择错误,请重新选择！/n");      break;    }  }  destroy(&mylist); //程序结束，摧毁链表}

#ifndef __SLIST_H__#define __SLIST_H__#include<cstdio>#include<malloc.h>#include<assert.h>typedef int ElemType;typedef struct Node { //定义单链表中的结点信息  ElemType data; //结点的数据域  struct Node *next; //结点的指针域}Node,*PNode;typedef struct List { //定义单链表的链表信息  PNode first; //first指向单链表中的第一个结点  PNode last; //last指向单链表中的最后一个结点  size_t size; //记录单链表中的结点个数}List;void InitList(List *list);//初始化单链表void push_back(List *list, ElemType x);//在单链表的末尾插入元素void push_front(List *list, ElemType x);//在单链表的头部插入元素void show_list(List *list);//打印单链表void pop_back(List *list);//删除单链表的最后一个元素void pop_front(List *list);//删除单链表的第一个元素void insert_val(List *list, ElemType val);//将数据元素插入到单链表中（要求此时单链表中的数据元素顺序排列）Node* find(List *list, ElemType x);//查找单链表中数据值为x的结点int length(List *list);//求单链表的长度void delete_val(List *list, ElemType x);//按值删除单链表中的某个数据元素void sort(List *list);//对单链表进行排序void reverse(List *list);//逆置单链表void clear(List *list);//清除单链表void destroy(List *list);//摧毁单链表//代码优化Node* CreateNode(ElemType x); //创建一个单链表结点Node* begin(List *list); //返回单链表的第一个结点Node* end(List *list); //返回单链表中最后一个结点的下一个结点void insert(List *list, Node *pos, ElemType x); //在单链表的特定位置（pos）插入新的结点#endif //__SLIST_H__

#include"slist.h"void InitList(List *list) {  list->first = list->last = (Node*)malloc(sizeof(Node)); //头结点  assert(list->first != NULL);  list->first->next = NULL;  list->size = 0;}//push_back的优化void push_back(List *list, ElemType x) {  insert(list, end(list), x);}//push_front的优化void push_front(List *list, ElemType x) {  insert(list, begin(list), x);}void show_list(List *list) {  //step 1：指针p指向单链表的第一个结点  Node *p = list->first->next;  //step 2：循环打印结点的信息  while (p != NULL) {    printf("%d->", p->data);    p = p->next;  }  printf("Nul./n");}void pop_back(List *list) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：定义指针p使其指向目标结点的前一个结点  Node *p = list->first;//从头结点开始  while (p->next != list->last)    p = p->next;  //step 3：删除目标结点  free(list->last);  list->last = p;  list->last->next = NULL;  //step 4：更新单链表的长度  list->size--;}void pop_front(List *list) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：定义指针p使其指向目标结点的前一个结点  Node *p = list->first->next;  //step 3：删除目标结点  list->first->next = p->next;  free(p);  //step 4：判断删除的结点是否是单链表的最后一个结点，若是则更新单链表的尾指针  if (list->size == 1)    list->last = list->first;  //step 4：更新单链表的长度  list->size--;}//insert_val的优化void insert_val(List *list, ElemType x) {  //step 1：创建一个新的结点  Node *s = CreateNode(x);  //step 2：定义指针p使其指向待插入位置的前一个结点  Node *p = list->first;//从头结点开始  while (p->next != NULL && p->next->data < s->data)    p = p->next;  //step 3：判断结点的待插入位置是否是表尾，若是则更新单链表的尾指针  if (p->next == NULL)    list->last = s;  //step 4：插入结点  s->next = p->next;  p->next = s;  //step 5：更新单链表长度  list->size++;}Node* find(List *list, ElemType x) {  //step 1：指针p指向单链表的第一个结点  Node *p = list->first->next;  //step 2：按照循环顺序查找链表结点  while (p != NULL && p->data != x)    p = p->next;  return p;}int length(List *list) {  return list->size;}void delete_val(List *list, ElemType x) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：确定结点在单链表中的位置，并判断其是否存在于单链表中  Node *p = find(list, x);  if (p == NULL) {    printf("要删除的数据不存在！/n");    return;  }  //step 3：判断结点位置是否是表尾  if (p == list->last)//是表尾    pop_back(list);  else {//不是表尾    Node *q = p->next;    p->data = q->data;    p->next = q->next;    free(q);    list->size--;  }}void sort(List *list) {  //step 1：判断单链表中的结点数是否为0或1  if (list->size == 0 || list->size == 1) return;  //step 2：将单链表中第一个结点之后的链表部分截出，方便重新按顺序插入链表之中  Node *s = list->first->next; // 指针s指向单链表的第一个节点  Node *p = s->next;//q指向s后面的结点  list->last = s;//单链表的尾指针指向单链表的第一个结点  list->last->next = NULL;//截断链表  //step 3：将截出的链表中的结点根据其数据域大小重新插入到原来链表中  while (p != NULL) {    s = p;    p = p->next;    Node *q = list->first;    while (q->next != NULL && q->next->data < s->data)      q = q->next;    if (q->next == NULL)//判断q此时指向的是否是单链表的最后一个结点，若是则更新链表的尾指针      list->last = s;    //将结点重新插入链表    s->next = q->next;    q->next = s;  }}void reverse(List *list) {  //step 1：判断单链表中的结点数是否为0或1  if (list->size == 0 || list->size == 1) return;  //step 2：将单链表中第一个结点之后的链表部分截出，然后将截出的链表中的结点按头插法重新插入到原链表中  Node *p = list->first->next;  Node *q = p->next;  list->last = p;  list->last->next = NULL;  while (q != NULL) {    p = q;    q = q->next;    p->next = list->first->next;    list->first->next = p;  }}void clear(List *list) {  //step 1：判断单链表是否为空  if (list->size == 0) return;  //step 2：释放单链表中的每一个结点  Node *p = list->first->next;  while (p != NULL) {    list->first->next = p->next;    free(p);    p = list->first->next;  }  //step 3：头指针和尾指针重新都指向头结点  list->last = list->first;  //step 4：更新链表长度  list->size = 0;}void destroy(List *list) {  //step 1：清空单链表  clear(list);  //step 2：释放头结点  free(list->first);  //step 3：头指针和尾指针都赋值为空  list->first = list->last = NULL;}//优化Node* CreateNode(ElemType x) {  Node *s = (Node*)malloc(sizeof(Node));  assert(s != NULL);  s->data = x;  s->next = NULL;  return s;}Node* begin(List *list) {  return list->first->next;}Node* end(List *list) {  return list->last->next;}void insert(List *list, Node *pos, ElemType x) {  //step 1：创建一个新的结点  Node *s = CreateNode(x);  //step 2：确定带插入位置  Node *p = list->first;  while (p->next != pos)    p = p->next;  //step 3：插入结点  s->next = p->next;  p->next = s;  //step 4：判断结点是否插入到链表的表尾，若是则更新单链表的表尾指针  if (pos == NULL)    list->last = s;  //step 5：更新单链表长度  list->size++;}

#include"slist.h"void main() {  List mylist;  InitList(&mylist);  ElemType item;  Node *p = NULL;  int select = 1;  while (select) {    printf("*******************************************/n");    printf("*[1] push_back    [2] push_front  */n");    printf("*[3] show_list    [4] pop_back   */n");    printf("*[5] pop_front    [6] insert_val  */n");    printf("*[7] find       [8] length    */n");    printf("*[9] delete_val    [10] sort     */n");    printf("*[11] reverse     [12] clear     */n");    printf("*[13*] destroy     [0] quit_system  */n");    printf("*******************************************/n");    printf("请选择：>>");    scanf("%d", &select);    if (select == 0) break;    switch (select) {    case 1:      printf("请输入要插入的数据（-1结束）:>");      while (scanf("%d", &item), item != -1) {        push_back(&mylist, item);      }      break;    case 2:      printf("请输入要插入的数据（-1结束）:>");      while (scanf("%d", &item), item != -1) {        push_front(&mylist, item);      }      break;    case 3:      show_list(&mylist);      break;    case 4:      pop_back(&mylist);      break;    case 5:      pop_front(&mylist);      break;    case 6:      printf("请输入要插入的数据:>");      scanf("%d", &item);      insert_val(&mylist, item);      break;    case 7:      printf("请输入要查找的数据:>");      scanf("%d", &item);      p = find(&mylist, item);      if (p == NULL)        printf("要查找的数据在单链表中不存在！/n");      break;    case 8:      printf("单链表的长度为%d/n", length(&mylist));      break;    case 9:      printf("请输入要删除的值:>");      scanf("%d", &item);      delete_val(&mylist, item);      break;    case 10:      sort(&mylist);      break;    case 11:      reverse(&mylist);      break;    case 12:      clear(&mylist);      break;      //case 13:      //destroy(&mylist);      //break;    default:      printf("选择错误,请重新选择！/n");      break;    }  }  destroy(&mylist); //程序结束，摧毁链表}