C Program for Doubly Linked List

Ram Pothuraju
/*Operations on Doubly linked list */
#include < stdio.h>

#include < conio.h>

typedef struct  node
 {
       int  data;
       struct node *next,*prev;

  }node;
node *start=NULL;
node *create(node *);
node *display(node *);
node *insert_beg(node *);
node *insert_end(node *);
node *insert_before(node *);
node *delete_beg(node *);
node *delete_end(node *);
node *delete_node(node *);
node *delete_after(node *);
node *delete_list(node *);

main()
 {
 int choice;
 clrscr();
 do
   {
  printf("\n1)Create a List.\n2)display\n3)Insert at beg\n4)Insert at end \n5)Insert before given node\n6)Delete from beg\n7)Delete from end\n8)Delete given node\n9)Delete node after given node\n10)Delete list");
  printf("\n11)Quit");
  printf("\nEnter your Choice : ");
  scanf("%d",&choice);

  switch(choice)
    {
   case 1: start=create(start);
    printf("\n Linked List created.");
    break;
   case 2: start = display(start);
    break;
   case 3: start = insert_beg(start);
    break;
   case 4: start = insert_end(start);
    break;
   case 5: start = insert_before(start);
    break;
   case 6: start = delete_beg(start);
    break;
   case 7: start = delete_end(start);
    break;
   case 8: start = delete_node(start);
    break;
   case 9: start = delete_after(start);
    break;
   case 10: start = delete_list(start);
    break;
  }
 }while(choice!=11);
 getch();
 return 0;
   }

node *create(node *start)
  {
 int val,n,i;
 node *new_node;
 printf("\n Enter no of data");
 scanf("%d",&n);
 for(i=0;i< n;i++)
    {
  printf("\n Next Data : ");
  scanf("%d",&val);
  if(start==NULL) // inserting the first node
       {
         start=(node *) malloc(sizeof(node));
         start->prev = NULL;
         start->data = val;
         start->next=NULL;
       }
  else
       {
   new_node=(node *) malloc(sizeof(node));
   new_node->prev = NULL;
   new_node->data=val;
   new_node->next=start;
   start->prev = new_node;
   start = new_node;
      }
    }

  return(start);
  }


node *display(node *start)
 {
 node *ptr;
 printf("\n Data stored in the Doubly linked list : ");
 ptr=start;
 printf("\n");




 if(start==NULL)
   printf("List is empty.\n");
 else
 {
   while(ptr != NULL)
   {
    printf("\t %d", ptr->data);
    ptr = ptr->next;
   }
 }
 return(start);
 }

node *insert_beg(node *start)
 {
 node *new_node;
 int no;
 printf("\n Enter data: ");
 scanf("%d",&no);
 new_node=(node*)malloc(sizeof(node));
 start->prev=new_node;
 new_node->next = start;
 new_node->prev=NULL;
 new_node->data = no;
 start = new_node;

 return(start);
 }

 node *insert_end(node *start)
 {
 node *new_node,*ptr;
 int no;
 printf("\n Enter data: ");
 scanf("%d",&no);
 new_node=(node*)malloc(sizeof(node));
 new_node->data = no;
 new_node->next = NULL;
 if(start==NULL)
 {
    new_node->prev=NULL;
    start=new_node;
 }
 else
 {  ptr=start;
    while(ptr->next != NULL)
        ptr=ptr->next;

 ptr->next=new_node;
 new_node->prev=ptr;
 }
 return(start);
 }
  node *insert_before(node *start)
 {
 node *new_node,*ptr;
 int val,no;
 if(start==NULL)
    start =insert_beg(start);
 else
 {
 printf("\n Enter data to insert: ");
 scanf("%d",&val);
 printf("\n Enter value before which data has to be inserted: ");
 scanf("%d",&no);
 new_node=(node*)malloc(sizeof(node));
 new_node->data = val;

 ptr=start;
 while(ptr->data != no)
     ptr = ptr->next;

 new_node->next = ptr;
 ptr->prev->next=new_node;
 ptr->prev=new_node;
       }
 return(start);
 }

 node *delete_beg(node *start)
 {
 node *p;

 p=start;
 if(p==NULL)
   printf("\n List is empty.");
 else
 {
   start=start->next;
   start->prev=NULL;
   free(p);
 }

 return(start);
 }
node *delete_end(node *start)
 {
 node *p;

 p=start;
 if(p==NULL)
   printf("\n list is empty.");
 else
 {
    while(p->next != NULL)
        p=p->next;

    p->prev->next=NULL;
    free(p);
 }
 return(start);
 }

node *delete_node(node *start)
 {
 node *ptr;
 int val;
 if(start==NULL)
    printf("\n List is empty.");
 else
 {
     printf("\n Enter value of node to be deleted; ");
     scanf("%d",&val);

     ptr=start;
     if(ptr->data == val)
     {
        start=delete_beg(start);
        return(start);
     }
     else
     {
        while(ptr->data != val)
        ptr=ptr->next;

        ptr->prev->next = ptr->next;
        ptr->next->prev = ptr->prev;
        free(ptr);
        return(start);
      }
 }
 }

 node *delete_after(node *start)
 {
 node *ptr,*p;
 int val;
 if(start==NULL)
    printf("\n List is empty.");
 else
 {
    printf("\n Enter value after which node has to be deleted: ");
    scanf("%d",&val);
    ptr=start;

    while(ptr->data != val)
       ptr=ptr->next;

    p = ptr->next;
    ptr->next = p->next;
    p->next->prev = ptr;
    free(p);
    return(start);
  }
 }
node *delete_list(node *start)
 {
  if(start==NULL)
      printf("\n List is empty.");
  else
  {
    while(start != NULL)
      start = delete_beg(start);
  }
  return(start);
 }





OUTPUT




1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 1

 Enter no of data 2

 Next Data : 11

 Next Data : 22

 Linked List created.
1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 4

 Enter data: 33



1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 5

 Enter data to insert: 11

 Enter value before which data has to be inserted: 22

1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 2

 Data stored in the Doubly linked list :
         0       11      22      11      33
1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 6

1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 7

1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 8

 Enter value of node to be deleted; 22

1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 9

 Enter value after which node has to be deleted: 11

1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 2

 Data stored in the Doubly linked list :
         11
1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 10

1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice : 2

 Data stored in the Doubly linked list :
List is empty.

1)Create a List.
2)display
3)Insert at beg
4)Insert at end
5)Insert before given node
6)Delete from beg
7)Delete from end
8)Delete given node
9)Delete node after given node
10)Delete list
11)Quit
Enter your Choice :

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