A simple example of a bidirectional linked list of C language data structures

Basic operation of bidirectional linked list

1. Using the tail insertion method to establish a two-way linked list.

2. Traversing a bidirectional list.

3. Implements the removal of a specified element from a bidirectional linked list.

4. Implement the insertion element e still - ordered algorithm in non - decreasing order bidirectional linked list.

5. Determines whether an element in a bidirectional list is symmetric if it returns 1 or 0.

6. If the element is a positive integer, the algorithm will arrange all odd Numbers before even Numbers.

7. Design a simple menu in the main function to debug the algorithm.

Example code:

// I'm not sorting because I didn't tell you whether the odd and even Numbers need to be sorted separately, so I'm not sorting, I'm just putting the odd Numbers after the even Numbers. 
// When I created the list, because the experiment didn't require the length of the list to be output, I typed it 1 A length of n The linked list. 
#include<stdio.h>
#include<stdlib.h>
struct node
{
 int data;
 node *pre,*next;
}*h,*end;
void CreatList()// create 1 Two two-way linked lists 
{
 int n;
 node *s,*e;
 printf(" Please enter the list length:     ");
 scanf("%d",&n);
 printf(" Please enter data:       ");
 h=(node *)malloc(sizeof(node));
 s=(node *)malloc(sizeof(node));
 h->pre=NULL;
 e=h;
 e->next=s;
 s->pre=e;
 while(n--)
 {
 e=s;
 scanf("%d",&s->data);
 s=(node *)malloc(sizeof(node));
 e->next=s;
 s->pre=e;
 }
 s->next=NULL;
 end=s;
 return ;
}
void PrintList()// The output list 
{
 node *s;
 s=h->next;
 printf(" Linked list data:        ");
 while(s!=end)
 {
 printf("%d ",s->data);
 s=s->next;
 }
 printf("\n");
 return ;
}
void DeletList()// Deletes an element from a linked list 
{
 int x;
 int flag;
 node *s,*e;
 printf(" Please enter the element to be deleted:    ");
 scanf("%d",&x);
 s=h->next;
 e=h;
 flag=0;
 while(s!=end)
 {
 if(s->data==x)
 {
  e->next=s->next;
  s->next->pre=e;
  free(s);
  flag=1;
  break;
 }
 e=s;
 s=e->next;
 }
 if(!flag)
 printf(" There is no value of %d The element. \n",x);// If it's not in the list x , output this sentence. 
 return ;
}
void InsetList()// Insert an element into an ordered list 
{
 int x;
 node *s,*e;
 printf(" Input the element to be inserted:   ");
 scanf("%d",&x);
 s=h->next;
 while(1)
 {
 if(s->data>=x)
 {
  e=(node *)malloc(sizeof(node));
  e->data=x;
  e->next=s;
  e->pre=s->pre;
  s->pre->next=e;
  s->pre=e;
  break;
 }
 else if(s==end)// will x Put it at the end of the list 
 {
  end=(node *)malloc(sizeof(node));
  s->data=x;
  end->pre=s;
  end->next=NULL;
  s->next=end;
  break;
 }
 s=s->next;
 }
 return ;
}
void JudgeList()// Determine if the bidirectional list is symmetric 
{
 node *s,*e;
 int flag=0;
 s=h->next;
 e=end->pre;
 while(s->data==e->data&&s!=end&&e!=h)
 {
 s=s->next;
 e=e->pre;
 }
 if(s==end&&e==h)
 printf(" The list is symmetric. \n");
 else
 printf(" Lists are asymmetric. \n");
 return ;
}
void SortList()// Place the odd Numbers in the list after the even Numbers 
{
 node *s;
 node *odd;
 int temp;
 odd=h->next;
 s=h->next;
 while(s!=end)
 {
 if(s->data%2!=0)
 {
  temp=odd->data;
  odd->data=s->data;
  s->data=temp;
  odd=odd->next;
  s=s->next;
 }
 else
  s=s->next;
 }
 return ;
}
int PrintMenu()// Printed catalogue 
{
 int T;
 printf("****************** directory ******************\n");
 printf(" create 1 Two two-way linked lists:            1\n");
 printf(" Output linked list:                2\n");
 printf(" Delete the specified element in the linked list:          3\n");
 printf(" Insert elements into the list:            4\n");
 printf(" Determine whether the linked list is symmetric:            5\n");
 printf(" Arrange the linked list:                6\n");
 printf(" End of operation:                0\n");
 printf(" Input operation instruction:      ");
 scanf("%d",&T);
 switch(T)
 {
 case 1:CreatList();break;
 case 2:PrintList();break;
 case 3:DeletList();break;
 case 4:InsetList();break;
 case 5:JudgeList();break;
 case 6:SortList();break;
 case 0:return 1;
 default:printf(" Typing error. Please enter again. \n");
 }
 return 0;
}
int main()
{
 int flag;
 while(1)
 {
 flag=PrintMenu();
 if(flag)// through flag Control the loop to jump out 
  break;
 }
 printf(" Thanks for using! \n");
 return 0;
}

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