title: insert a node at end and delete a node at beginning in double linked list
body: <p>Double linked list program </p>
  
  <pre><code>#include&lt;stdio.h&gt;
  #include&lt;stdlib.h&gt;
  
  struct node  
  {
      int data;
      struct node *rnext;
      struct node*lnext;
  }*first=NULL,*last=NULL;
  
  void  display()
  {
      struct node*temp;
  
      if(first==NULL)
      {
          printf("list is empty\n");
          return;
      }
  
      temp=first;
  
      while(temp!=NULL)
      {
          printf("%d \n",temp-&gt;data);
          temp=temp-&gt;rnext;
      }
  }
  
  void  insertion()
  {
      struct node *temp;
      struct node *nn= (struct node*) malloc(sizeof(struct node));
      printf("enter data to be inserted\n");
      nn-&gt;rnext=NULL;
      last-&gt;rnext=nn;
      nn-&gt;lnext=last;
      last=nn;
  }
  
  void deletion()
  {
      struct node *temp;
  
      if(first==NULL||last==NULL)
      {
          printf("list is empty\n");
          return;
      }
  
      temp=first;
      first=first-&gt;rnext;
      first-&gt;lnext=NULL;
      free(temp);
  }
  
  /* main loop */
  
  int  main()    
  {
      int option;
      do
      {
          printf("enter option 1.insertion\n2.display\n3.deletion\n4.exit\n");
          scanf("%d",&amp;option);
          switch(option)
          {
              case 1:
                  insertion();
                  break;
              case 2:
                  display();
                  break;
              case 3:
                  deletion();
                  break;
          }
      } while(option!=4);
  }
  </code></pre>
  
  <p>i have wrote a double linked list to insert a node at end and delete a node at             beginning in linux using C language.
      but while executing the program getting the error segmentation fault.
      i am also posting the output.</p>
  
  <pre><code>./out
  enter option 1.insertion
  2.display
  3.deletion
  4.exit
  1
  enter data to be inserted
  12 
  Segmentation fault
  please help me with the solution for segmentation fault             
  </code></pre>
  
  <p>this is my code please help me run it and debug it .I am inserting the node at the end and deleting the node at the end </p>