doubly linked list c code – delete insert

Doubly linked list c – delete – insert

Linked list is a linear data structure. Doubly linked list c contains collection of nodes, which contains two pointers, one pointing to the next pointer, while other pointing to the previous pointer as shown below while for simple linked list implementation in c program, only one pointer is available . For making c program of doubly linked list we will have two struct pointer which would remain at constant place, i.e at first and last as “*head” and “*last”. You can also see for various data structure c program examples.

doubly-linked-list-c-code
doubly-linked-list-c-code
Doubly linked list c code – delete – insert
#include<stdio.h>
#include<conio.h>
#include<stdlib.h> 
struct node
{
     struct node *previous;
     int data;
     struct node *next;
}*head, *last; 

void insert_begning(int value)
{
    struct node *var,*temp;
     var=(struct node *)malloc(sizeof(struct node));
     var->data=value;
     if(head==NULL)
     {
         head=var;
         head->previous=NULL;
         head->next=NULL;
         last=head;
     }
     else
     {
         temp=var;
         temp->previous=NULL;
         temp->next=head;
         head->previous=temp;
         head=temp;
     }
} 

void insert_end(int value)
{
     struct node *var,*temp;
     var=(struct node *)malloc(sizeof(struct node));
             var->data=value;
     if(head==NULL)
     {
          head=var;
          head->previous=NULL;
          head->next=NULL;
          last=head;
     }
     else
     {
         last=head;
         while(last!=NULL)
         {
             temp=last;
             last=last->next;
         }
     last=var;
     temp->next=last;
     last->previous=temp;
     last->next=NULL;
     }
}   

int insert_after(int value, int loc)
{
     struct node *temp,*var,*temp1;
     var=(struct node *)malloc(sizeof(struct node));
     var->data=value;
         if(head==NULL)
     {
           head=var;
           head->previous=NULL;
           head->next=NULL;
     }
     else
     {
           temp=head;
           while(temp!=NULL && temp->data!=loc)
           {
                 temp=temp->next;
           }
           if(temp==NULL)
           {
                printf("\n%d is not present in list ",loc);
           }
           else
           {
           temp1=temp->next;
           temp->next=var;
           var->previous=temp; 
          var->next=temp1;
           temp1->previous=var;
           }
     }
     last=head;
     while(last->next!=NULL)
     {
           last=last->next;
     }
}   
int delete_from_end()
{
      struct node *temp;
      temp=last;
      if(temp->previous==NULL)
      {
           free(temp);
           head=NULL;
           last=NULL;
           return 0;
      }
      printf("\nData deleted from list is %d \n",last->data);
      last=temp->previous;
      last->next=NULL;
      free(temp);
      return 0;
} 

int delete_from_middle(int value)
{
    struct node *temp,*var,*t, *temp1;
    temp=head;
    while(temp!=NULL)
    {
        if(temp->data == value)
        {
             if(temp->previous==NULL)
             {
                  free(temp);
                  head=NULL;
                  last=NULL;
                  return 0;
             }
             else
             {
                  var->next=temp1;
                  temp1->previous=var;
                  free(temp);
                  return 0;
             }
        }
        else
        {
              var=temp;
              temp=temp->next;
              temp1=temp->next;
        }
    }
    printf("data deleted from list is %d",value);
}  

void display()
{
     struct node *temp;
     temp=head;
     if(temp==NULL)
      {
         printf("List is Empty");
      }
     while(temp!=NULL)
     {
          printf("-> %d ",temp->data);
          temp=temp->next;
     }
} 

int main()
{
    int value, i, loc;
    head=NULL;
    printf("Select the choice of operation on link list");
    printf("\n1.) insert at begning\n2.) insert at at\n3.) insert at middle");
    printf("\n4.) delete from end\n5.) reverse the link list\n6.) display list\n7.)exit");
    while(1)
    {
          printf("\n\nenter the choice of operation you want to do ");
          scanf("%d",&i);
          switch(i)
          {
                case 1:
                {
                 printf("enter the value you want to insert in node ");
                 scanf("%d",&value);
                 insert_begning(value);
                 display();
                 break;
                 }
                 case 2:
                 {
                 printf("enter the value you want to insert in node at last ");
                 scanf("%d",&value);
                 insert_end(value);
                 display();
                 break;
                 }
                 case 3:
                 {
                 printf("after which data you want to insert data ");
                 scanf("%d",&loc);
                 printf("enter the data you want to insert in list ");
                 scanf("%d",&value);
                 insert_after(value,loc);
                 display();
                 break;
                 }
                 case 4:
                 {
                 delete_from_end();
                 display();
                 break;
                 }
                 case 5:
                 {
                 printf("enter the value you want to delete");
                 scanf("%d",value);
                 delete_from_middle(value);
                 display();
                 break;
                 }
                 case 6 :
                 {
                 display();
                 break;
                 }
                 case 7 :
                 {
                      exit(0);
                      break;
                 }
          }
    }
    printf("\n\n%d",last->data);
    display();
    getch();
}

Output:

doubly-linked-list-c-code
doubly-linked-list-c-code
Doubly linked list c code – delete – insert




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