C program for Doubly Linked List

This program is for Doubly linked list in C language.
It can perform Doubly linked list insertion at any place in linked list, deletion and displaying list.

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#include <stdio.h> #include<conio.h> #include<stdlib.h> struct node { int info; struct node *rptr; struct node *lptr; } *l,*r,*temp,*dis; void insertfirst() { int i,j; //struct node *cout; printf("\nEnter the data:"); scanf("%d",&i); temp=(struct node*) malloc(sizeof(struct node)); temp->info=i; if (r==NULL) { temp->rptr=NULL; temp->lptr=NULL; l=temp; r=temp; } else //if(j==l->info) { temp->lptr=NULL; temp->rptr=l; l=temp; } } void insertmid() { int j; printf("\nEnter the data before which u want to insert the data:"); scanf("%d",&j); struct node *cout; if(j==l->info) { temp->lptr=NULL; temp->rptr=l; l=temp; } else { cout=l; while ((cout->rptr)->info!=j && cout->rptr!=NULL) { cout=cout->rptr; } if(cout->rptr==NULL) { printf("\nEntered data not found before which new node will be inserted\n!!CHECK the entered data"); } else { temp->rptr=cout->rptr; cout->rptr=temp; temp->lptr=cout; (temp->rptr)->lptr=temp; } } } void insertend() { struct node *cout; cout=l; while (cout->rptr!=NULL) { cout=cout->rptr; } cout->rptr=temp; temp->lptr=cout; temp->rptr=NULL; r=temp; } void delet() { int k; struct node *tem; tem=l; printf("\nEnter the node's data to be deleted\nNOTE:(if data is repeated the left most data of them will be deleted):"); scanf("%d",&k); if(l->info==k) { l=l->rptr; l->lptr=NULL; tem->rptr=NULL; free(tem); printf("\nNode deleted"); } else { while(tem->info!=k && tem->rptr!=NULL) { tem=tem->rptr; } if(tem->rptr==NULL) { if(tem->info==k) { (tem->lptr)->rptr=NULL; r=tem->lptr; tem->lptr=NULL; free(tem); printf("\nNode deleted\n"); } else { printf("\n!!!Info not found Enter appropriate data\n"); } } else { (tem->rptr)->lptr=(tem->lptr); (tem->lptr)->rptr=tem->rptr; tem->rptr=tem->lptr=NULL; printf("\nNode deleted\n"); } } } void display() { dis=l; if(l==NULL) { printf("\n\t!!!Linked List Empty!!!\n\t\tFirst enter some elements."); } else { printf("\n\t\tThe Doubly Linked List is as below:\n"); do { printf("%d<==>",dis->info); dis=dis->rptr; } while(dis->rptr!=NULL); printf("%d<=>NULL",dis->info); printf("\nLeft most node =%d\nRight most node =%d",l->info,r->info); } } void main() { int i; char ch; clrscr(); do { printf("\nWhat do u want to do with doubly inked list:\n"); printf("\n1)Insertion at first node\n2)Insertion in between\n3)Insertion at end\n4)display\n5)Deletion\n"); scanf("%d",&i); switch(i) { case 1: insertfirst(); break; case 2: insertmid(); break; case 3: insertend(); break; case 4; display(); break; case 5: delet(); break; deafault: printf("\n\n!!!!!Not a Valid choice!!!!!"); break; } printf("\ndo u want to continue?(y/n)\n"); ch=getch(); } while(ch=='y'||ch=='Y'); }

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ENJOY....