Introduction to the basic application of two way linked list insertion and deletion

Double linked list is nothing but an extra front chain, right
Definition of double linked list

 
struct DNode 
{ 
int data; 
struct DNode *next; 
struct DNode *pre; 
}; 

Definition of a single linked list

 
view plaincopy 
struct DNode 
{ 
int data; 
struct DNode *next; 
}; 

The rest of you can read a blog post about the same

 
#ifndef HEAD_H 
#define HEAD_H 
#include <iostream> 
using namespace std; 
#include <cassert> 
#include <cstdlib> 
#include <cmath> 
#include <sstream> 
#include <fstream> 
#include <string> 
#include <algorithm> 
#include <list> 
#include <queue> 
#include <vector> 
#include <deque> 
#include <stack> 
#include <bitset> 
#include <set> 
#include <map> 
#endif 
struct DNode 
{ 
int data; 
struct DNode *next; 
struct DNode *pre; 
}; 
DNode *Creat() 
{  
DNode *head,*p,*s; 
head=(DNode *)malloc(sizeof(DNode)); 
p=head; 
int temp; 
while (cin>>temp&&temp) 
{ 
s=(DNode *)malloc(sizeof(DNode)); 
s->data=temp; 
p->next=s; 
s->pre=p; 
p=s; 
} 
head=head->next; 
p->next=NULL; 
head->pre=NULL; 
return (head); 
} 
DNode *Insert(DNode *&head,int num) 
{ 
DNode *p,*s; 
s=(DNode *)malloc(sizeof(DNode)); 
s->data=num; 
p=head; 
while (NULL!=p->next&&num>p->data) 
{ 
p=p->next; 
} 
if (num<=p->data) 
{ 
if (NULL==p->pre) 
{ 
s->next=head; 
head->pre=s; 
head=s; 
head->pre=NULL; 
} 
else 
{ 
s->pre=p->pre; 
p->pre->next=s; 
s->next=p; 
p->pre=s; 
} 
} 
else 
{ 
p->next=s; 
s->pre=p; 
s->next=NULL; 
} 
return(head); 
} 
DNode *Del(DNode *&head,int num) 
{ 
DNode *p; 
p=head; 
while (NULL!=p->next&&num!=p->data) 
{ 
p=p->next; 
} 
if (num==p->data) 
{ 
if (NULL==p->pre) 
{ 
head=p->next; 
p->next->pre=head; 
free(p); 
} 
else if (NULL==p->next) 
{ 
p->pre->next=NULL; 
free(p); 
} 
else 
{ 
p->pre->next=p->next; 
p->next->pre=p->pre; 
free(p); 
} 
} 
else 
{ 
cout<<num<<" cound not be found"<<endl; 
} 
return head; 
} 
void Display(DNode *head) 
{ 
DNode *p; 
p=head; 
while (NULL!=p) 
{ 
cout<<(p->data)<<" "; 
p=p->next; 
} 
cout<<endl; 
} 

 
#include "head.h" 
int main() 
{ 
DNode *head; 
head=Creat(); 
Display(head); 
#ifndef DEBUG 
cout<<"please input an num to insert:"; 
#endif 
int insert_num; 
while (cin>>insert_num&&insert_num) 
{ 
Insert(head,insert_num); 
Display(head); 
} 
#ifndef DEBUG 
cout<<"please input an number to delete:"; 
#endif 
int delete_num; 
while (cin>>delete_num&&delete_num) 
{ 
Del(head,delete_num); 
Display(head); 
} 
return (EXIT_SUCCESS); 
}