Write A Program For Erasing A linked list

Program

Here is a complete program that erases a list pointed to by p by adding the nodes of a list pointed by p to the free list.

# include <stdio.h>
# include <stdlib.h>
struct node
{
int data;
struct node *link;
};
struct node *insert(struct node *, int);
void erase(struct node **,struct node **);
void printlist ( struct node * );

void erase (struct node **p, struct node **free)
{
   struct node *temp;
   temp = *p;
   while (temp->link != NULL)
         temp = temp ->link;
   temp->link = (*free);
   *free = *p;
   *p = NULL;
}

struct node *insert(struct node *p, int n)
{
   struct node *temp;
   if(p==NULL)
   {
      p=(struct node *)malloc(sizeof(struct node));
      if(p==NULL)
      {
   printf("Error\n");
          exit(0);
      }
      p-> data = n;
      p-> link = NULL;
   }
   else
   {
     temp = p;
     while (temp-> link!= NULL)
    temp = temp-> link;
    temp-> link = (struct node *)malloc(sizeof(struct node));
    if(temp -> link == NULL)
    {
  printf("Error\n");
         exit(0);
      }
    temp = temp-> link;
      temp-> data = n;
      temp-> link = NULL;
      }
      return (p);
}

void printlist ( struct node *p )
{
      printf("The data values in the list are\n");
      while (p!= NULL)
      {
   printf("%d\t",p-> data);
         p = p-> link;
      }
   }

   void main()
   {
         int n;
         int x;
         struct node *start = NULL ;
         struct node *free=NULL;

         /* this code will create a free list for the test purpose*/
        printf("Enter the number of nodes in the initial free list \n");
         scanf("%d",&n);
         while ( n-- > 0 )
         {
            printf( "Enter the data values to be placed in a node\n");
            scanf("%d",&x);
            free = insert ( free,x);
         }

            /* this code will create a list to be erased*/
           printf("Enter the number of nodes in the list to be created for
erasing \n");
            scanf("%d",&n);
            while ( n-- > 0 )
            {
               printf( "Enter the data values to be placed in a node\n");
               scanf("%d",&x);
               start = insert ( start,x);
            }
               printf("The free list islist is:\n");
               printlist ( free );
               printf("The list to be erased is:\n");
               printlist ( start);
               erase(&start,&free);
               printf("The free list after adding all the nodes from the list to
be erased is:\n");
               printlist ( free );
   }