c++实现单链表创建，删除，遍历，插入，修改操作

#include<iostream>    
#include<string>  
#include<malloc.h>    
using namespace std;    

struct Node    
{   
  int data;
  struct Node* next;    
};    

struct Node* build_list(int n)   
{    
  Node *head =(struct Node*)malloc(sizeof(Node));
  if (head == NULL)
  {
    cout<<"malloc failed!"<<endl;  
    return head;
  } 
  head->data = 1;
  head->next = NULL;

  Node *curNode = head;
  for (int i=1;i<n;i++)
  {
    Node *newNode = (struct Node*)malloc(sizeof(Node));
    if (newNode == NULL)
    {
      cout<<"malloc failed!"<<endl;  
      return head;
    }
    newNode->data = i+1;
    newNode->next = NULL;

    curNode->next = newNode;
    curNode = newNode;
  }     
  return head;    
}
struct Node* addtail_node_list(struct Node* head, struct Node* newNode)
{
  if (head == NULL || newNode == NULL)
  {
    return head;
  }
  struct Node* pcurrNode=head; 
  while(pcurrNode->next != NULL)    
  {
    pcurrNode = pcurrNode->next;    
  }
  if (pcurrNode != NULL)
  {
    pcurrNode->next = newNode;
    newNode->next = NULL;
  }
  return head;
}

struct Node* addprev_node_list(struct Node* head, struct Node* newNode,int key)
{
  if (head == NULL || newNode == NULL)
  {
    return head;
  }
  struct Node* pcurrNode = head;
  struct Node* pprevNode = NULL;
  while(pcurrNode != NULL)    
  {
    if (pcurrNode->data == key)
    {
      if (pcurrNode == head)
      {
        newNode->next = head;
        head = newNode;
      }
      else
      {
        pprevNode->next = newNode;
        newNode->next = pcurrNode;
      }
      break;
    }
    pprevNode = pcurrNode;
    pcurrNode = pcurrNode->next;    
  }
  return head;
}

struct Node* modkey_node_list(struct Node* head, int key, int modval)
{
  if(head==NULL)  
  {
    return head;  
  }

  struct Node* pCurrNode=head;  
  while(pCurrNode!=NULL)  
  {  
    if (pCurrNode->data == key)
    {
      pCurrNode->data = modval;
      break;
    }
    pCurrNode=pCurrNode->next;  

  } 

  return head;
}

struct Node* query_node_list(struct Node* head, int key)
{
  if(head==NULL)  
  {
    return head;  
  }

  struct Node* pCurrNode=head;   
  while(pCurrNode!=NULL)  
  {  
    if (pCurrNode->data == key)
    {
      return pCurrNode;
    }
    pCurrNode=pCurrNode->next;  

  } 

  return NULL;
}
struct Node* delete_node_list(struct Node* head, int key)   
{  
  if(head==NULL)  
  {  
    cout<<"list is null"<<endl;  
    return head;  
  }

  struct Node* pCurrNode = head;   
  struct Node* pPrevNode = NULL;
  bool bfind = false;
  while(pCurrNode!=NULL)  
  {  
    if (pCurrNode->data == key)
    {
      if(head==pCurrNode)  
      {  
        head=pCurrNode->next; 
      }
      pPrevNode->next = pCurrNode->next;
      pCurrNode->next = NULL;
      free(pCurrNode);

      bfind = true;
      break;
    } 
    pPrevNode = pCurrNode;
    pCurrNode=pCurrNode->next;  

  } 
  if (!bfind)
  {
    cout<<key<<" not find"<<endl;
  }
  return head;  
}  

void print_list(struct Node* head)   
{    
  struct Node* pcurrNode=head;  
  while(pcurrNode!=NULL)    
  {    
    cout<<pcurrNode->data<<" "; 

    pcurrNode = pcurrNode->next;    
  }  
  cout<<endl;       
}    

int main(void)  
{
  Node *head=build_list(10);
  if (head == NULL)
  {
    getchar();
    return -1;
  }
  cout<<"pint build list"<<endl;
  print_list(head); 

  Node *newNode = (struct Node*)malloc(sizeof(Node));
  int newvalue = 57;
  if (newNode == NULL)
  {
    cout<<"malloc failed!"<<endl;  
    return -1;
  }
  newNode->data = newvalue;
  newNode->next = NULL;
  cout<<"construct a new node:"<<newNode<<endl;
  addtail_node_list(head,newNode);

  Node *tmp = query_node_list(head,newvalue);
  cout<<"query the node:"<<tmp<<" key:"<<newvalue<<endl;

  modkey_node_list(head,newvalue,27);
  cout<<"mod the key "<<newvalue<<" as key "<<27<<endl;
  int key = 7;
  cout<<"after delete key equal 7"<<endl;
  head=delete_node_list(head,key);   

  print_list(head); 

  Node *newNode1 = (struct Node*)malloc(sizeof(Node));
  if (newNode1 == NULL)
  {
    cout<<"malloc failed!"<<endl;  
    return -1;
  }
  newNode1->data = 7;
  newNode1->next = NULL;
  head = addprev_node_list(head,newNode1,8);
  cout<<"after add key of 8"<<endl;
  print_list(head);

  getchar();

  return 0;    
}