Basic Operations of Pointer Nodes

#include<stdio.h>
#include<conio.h>

 struct node
  {
   int info;
   node *next;
  }*start,*nptr,*save,*ptr,*end;

 node *create(int);
 int new_node_input();
 void insert_node(node *,int);
 void display_node(node *);
 void del_node(node *,int);

 void main()
 {
 clrscr();
 int choice,inf;
 start = end = NULL;
 inf = new_node_input();
 nptr = create(inf);
 insert_node(nptr,1);
 display_node(start);
 do
 {
 printf("\n\n\t\t What Would Like To Do Now ? \n");
 printf("\n 1. Inserting Node From the Beginning ");
 printf("\n 2. Inserting Node From the End ");
 printf("\n 3. Deleting Node From the Beginning");
 printf("\n 4. Deleting Node From the End");
 printf("\n\t\t ..... Hit Other Keys To Exit .....");
 printf("\n\n Enter your choice : ");
 scanf("%d",&choice);
 switch(choice)
  {
  case 1 :
  case 2 : inf = new_node_input();
  nptr = create(inf);
  insert_node(nptr,choice);
  break;

  case 3 :
  case 4 : del_node(nptr,choice);
  break;

  default : break;
  }
 display_node(start);
 }while((choice>=1)&&(choice<=4));
 printf("\n\n\t\t !!!! Thanks Fro Using The Program !!!!");
 getch();
 }

 int new_node_input()
 {
  int number;
  printf("\n Enter The Information For The New Node : ");
  scanf("%d",&number);
  return number;
 }

 node *create(int number)
 {
  ptr = new node;
  ptr->info = number;
  ptr->next = NULL;
  return ptr;
 }

 void insert_node(node *np,int choice)
 {
  printf("\n\n\t\tInsertion has been done \n\n");
  getch();
  if(start == NULL)
   start = end = np;
  else
  {
   if(choice == 1)
   {
   save = start;
   start = np;
   np->next = save;
   }
   else
   {
   end->next = np;
   end  = np;
   }
  }
 }

 void display_node(node *np)
 {
  printf("\n\n Now The List Is : \n\t");
  while(np != NULL)
  {
   printf("%d ->",np->info);
   np = np->next;
  }
 }

 void del_node(node *np,int choice)
 {
  printf("\n\n\t\tDeletion has been done \n\n");
  getch();
  if(start == NULL)
   printf("\n\nUNDERFLOW !!!\n\n");
  else
  {
   if (choice == 3)
   {
    np = start;
    start = start->next;
   }
   else
   {
    np = end;
    end = NULL;
   }
   delete np;
  }
 }