list.h
======
#define   NULL   0         /*  linear list header file  */
typedef   char   DATA;     /*  will use char in examples  */

struct linked_list {
   DATA                 d;
   struct linked_list   *next;
};


list.c
======
typedef   struct linked_list   ELEMENT;
typedef   ELEMENT              *LINK;
#include   <stdio.h>
#include   <stdlib.h>
#include   "list.h"

LINK   string_to_list(char []);
void   print_list(LINK);
int    count(LINK);

main()
{
   LINK   h;

   h = string_to_list("ABC");
   printf("The resulting list is\n");
   print_list(h);
   printf("\nThis list has %d elements.\n", count(h));
}


Output
======
The resulting list is
A --> B --> C --> NULL
This list has 3 elements.

LINK string_to_list(char s[])
{
   LINK   head;

   if (s[0] == '\0')     /* base case */
      return NULL;
   else {
      head = malloc(sizeof(ELEMENT));
      head -> d = s[0];
      head -> next = string_to_list(s + 1);
      return head;
   }
}


void print_list(LINK head)
{
   if (head == NULL)
      printf("NULL");
   else {
      printf("%c --> ", head -> d);
      print_list(head -> next);
   }
}


int count(LINK head)
{
   if (head == NULL)
      return 0;
   else
      return (1 + count(head -> next));
}