Exercise 12-13 - CBD page 426 - Lone Leth Thomsen

/* Kelly & Pohl Exercise 12.13, p. 426  */
/*                                     */
/* Lone Leth Thomsen, 11. April 2003   */

#include <stdio.h>
#include <stdlib.h>

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

int count_i(LINK l){
	int i = 0;
	while (l != NULL){
		i++;
		l = l->next ;
	};
	return i;
};

	int count_r(LINK l){ if (l == NULL) return 0; else return(1+ count_r(l->next )); };
	is a recursive definition inspired by the count example on p. 411. The function count_r recursively counts the number of elements in a linked list.If the list is empty, 0 is returned, else 1 is added to the result of calling the count_r function recursively on the tail of the list.

 

	int count_i(LINK l){ int i = 0; while (l != NULL){ i++; l = l->next ; }; return i; };
	is an iterative version of the count function, called count_i. A variable i is set to 0 (the counter). Then as long as there are elements in the list, 1 is added to i. Finally i is returned when the end of the list is reached.