Single linked list basic operation

Header file #pragma once#include <stdio.h> #include  <assert.h> #include  <malloc.h > #include  <stdlib.h>typedef int DateType;typedef struct LinkNode{  Datetype _data; struct  linknode* _next;}  linknode;void printlist (linknode* phead)   //Print { linknode* begin =  pHead; while  (begin != null)  {  printf ("%d->",  begin->_ Data)   begin = begin->_next;   //here to note, do not write the reverse:begin->_next=begin;   } printf ("null\n");} Linknode* buynode (DATETYPE&NBSP;X)      //initialization Node { linknode* tmp =   (linknode*) malloc (sizeof (Linknode)); if  (tmp == null)  {  printf (" Malloc faile ");   exit ( -1); } tmp->_next = null; tmp->_data  = x; return tmp;} void Pushfront (linknode*& phead, datetype x)//head Insert { //empty list  if  (phead ==  NULL)    //proves to be empty linked list, need to open node  {  phead = buynode (x);  } else {   linknode* nownode = buynode (x);  nownode->_next = phead;   //the head pointer to my _next, I point to you, realize the fork   phead = nownode; }}void popfront ( Linknode*& phead)//First Delete, there are three kinds of situation:{                                          if  (phead == null)     //   Air          {                                       return; } else if  (PHead->_next  == null)     //    one node  {  free (phead);   phead = null; } else                                 //    two nodes and above  {                                       LinkNode*del = pHead;       //Save the back node first, then the previous delete   phead = phead->_next;  free (DEL);  } Void pushback (linknode*& phead, datetype x)//tail plug { // if  (phead ==  null)    //CertificateMing is the empty list, need to open up the node  {  phead = buynode (x);  } else {  linknode*  tail = pHead;  while  (tail->_next != null)   // Note that the conditions of the loop cannot be written  tail != NULL  {   tail = tail->_next;   }  tail->_next = buynode (x);  }}void popback (LinkNode*& pHead)      //tail { if  (phead == null)               //No Nodes       {  return;  } else if  (phead->_next == null)   //a node  {  free (pHead);   pHead = NULL; } else                          //  Two nodes and above &NBSP;{&NBSP;&NBSP;//LINKNODE*&Nbsp;cur = phead;      //This requires two pointers, one after the other, since deleting a node requires the previous node   // linknode* prev = null;  //while  (cur->_next != null)             //Note that the conditions of the cycle cannot be written  cur != null  //{   // prev = cur;  // cur = cur->_next;  //}   //prev->_next = null;  //free (cur);   //or the following method:   linknode* prevtail = phead;  while  (prevtail->_next->_next!=null)    {   prevtail = prevtail->_next;  }  free (prevTail->_ Next);   prevtail->_next = null; }}linknode* find (LinkNode* pHead, DATETYPE&NBSP;X)//  Find a number { linknode* cur = phead; while  (cur)  {   if  (CUR-&GT;_DATA&NBSP;==&NBSP;X)   {   return cur;  }  cur = cur->_next;  } return null;} Void insert (linknode* pos, datetype x)   //arbitrary position Insert { linknode* tmp =  buynode (x);  assert (POS);  tmp->_next = pos->_next;  //this way, pay special attention to, . Pos->_next = tmp; /*linknode* tmp = buynode (x);  LinkNode* next  = null; assert (POS); next = pos->_next; pos->_next = tmp;    tmp->_next = next;*/}void erase (linknode*& phead,linknode*  POS)   //Delete a node { assert (POS);  //pos is the head node  //pos is the intermediate node  if  (phead ==  POS)      //only one node  {  LinkNode* del = pos;   Phead = phead->_next;  free (del);  } else        //There are multiple node conditions  {  //pos not in the list   LinkNode* prev = pHead;   while  (Prev && prev->_next != pos)   {    prev = prev->_next;  }  if  (prev)   {    Prev->_next = pos->_next;   free (POS);  } }}linknode*  Reverse (linknode*& phead)      //reverse chain list { linknode* cur =  phead; linknode* newhead = null; linknode* tmp; while  (cur)  {    tmp = cur;  cur = cur->_next;  tmp->_next  = newhead;  newhead = tmp; } return newhead;} Linknode* findmidnode (linknode* phead)    //Find middle Node { linknode* first =  phead; linknode* second = phead; while  (second->_next != null)  {  if  (second->_next->_next  == null)   {   return first;   break;  }   else  {   first = first->_next;   second  = second->_next->_next;  } } return first;} Linknode* findnodefromback (linknode* phead, int x)//Find the penultimate x node { int i =  0; linknode*first = phead; linknode*second = phead; while  (first  &&  (i < x)  {  first = first->_next;  i++;  } if  (i < x)  {  return NULL; } while  (first)  {  first = first->_next;  second = second->_next; }  return second;} Delete a non-tailed node of a headless single-linked list Int geTlistlength (Linknode* phead)    //get the chain table length { int count = 0; linknode*  begin = pHead; while  (BEGIN)  {  count++;  begin =  begin->_next; } return count;} Void destorylist (linknode*& phead)    //Delete all nodes { linknode* begin =  pHead; while  (BEGIN)  {     LinkNode* del = begin;   begin = begin->_next;  free (del);  } phead = null;} Source file #include  "Slist.h" void test1 ()//Head action { linknode* phead = null; //head pointer  pushfront (phead, 1);  pushfront (phead, 2);  pushfront (phead, 3);  PushFront ( PHEAD,&NBSP;4);  printlist (phead);//Print  popfront (phead);  popfront (Phead);  popfront (PHead);  popfront (Phead);  popfront (Phead);  printlist (phead);//Print}void tesT2 ()//tail operation { linknode* phead = null; pushback (phead, 1);  pushback (PHead, &NBSP;2);  pushback (phead, 3);  pushback (phead, 4);  printlist (pHead);//Print  popback ( Phead);  popback (Phead);  popback (Phead);  popback (Phead);  popback (Phead);  PrintList ( Phead)///print}VOID&NBSP;TEST3 ()//Get the list length { linknode* phead = null; pushback (pHead, 1 );  pushback (phead, 2);  pushback (phead, 3);  pushback (phead, 4);  PrintList ( Phead);//Print  int ret = getlistlength (phead);  printf ("%d\n", ret);} VOID&NBSP;TEST4 ()//delete entire list { linknode* phead = null; pushback (phead, 1);  Pushback (phead, 2);  pushback (phead, 3);  pushback (phead, 4);  PrintList (pHead);// Print   destorylist (phead);  printlist (Phead);} VOID&NBSP;TEST5 ()//Find a number to find this number after inserting a number { linknode* phead = null; pushback (Phead, 1);  pushback (phead, 2);  pushback (phead, 3);  pushback (pHead, 4);  Printlist (Phead);  linknode* ret = find (phead, 2);  printf ("%d\n",  ret->_ data);  insert (ret, 8);    //after finding 2, insert a 8 printlist (Phead) in the back of 2; ret =  Find (phead, 7);    //7 does not exist  printf ("ret=null:%p\n",  ret);} Void test6 ()             //deletes the number of the specified position {  Linknode* phead = null; pushback (phead, 1);  pushback (pHead, 2);  Pushback (phead, 3);  pushback (phead, 4);  printlist (phead);  linknode* ret =  find (PHEAD,&NBSP;2);  erase (Phead,ret);   //after finding 2, remove 2  printlist (phead);} VOID&NBSP;TEST7 ()             //Find the middle node {  Linknode* phead = null; pushback (phead, 1);   Pushback (phead, 2);  pushback (phead, 3);  pushback (phead, 4);  PushBack (PHead, &NBSP;5);  pushback (phead, 6);  //pushback (phead, 7);  printlist (pHead);  LinkNode*  ret=reverse (Phead);  printlist (ret);  /*linknode*ret=findmidnode (Phead);  printf ("%d\n",  ret->_data); */}void test8 ()              //returns the penultimate K node { linknode* phead = null; pushback (phead, 1);  PushBack ( PHEAD,&NBSP;2);  pushback (phead, 3);  pushback (phead, 4);  pushback (pHead, 5);  pushback (phead, 6);  printlist (Phead);  linknode* ret = findnodefromback ( phead,3)  printf ("%d\n",  ret->_data);  /*linknode*ret=findmidnode (Phead);  printf ("%d\n",  ret->_data); */}int main () { //test1 ();  //test2 ();  //test3 ();  //test4 ();  Test5 ();  //test6 ();  //test7 ();  test8 ();  return 0;} 

Single linked list basic operation