Simple Linked List

Simple LinkedList

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

#ifndef __cplusplus
typedef char bool;
#define true 1
#define false 0
#endif

struct list_element {

	struct list_element *next;
};

typedef struct list_element list_element;

typedef struct  {
	/* data */
	list_element *first;
	list_element *last;

} list;

void list_init(list *container) {

   container->first = 0;
   container->last = 0;
}

bool list_empty(list *container) {

	return 0 == container->first;
}

list_element *list_begin(list *container) {

	return container->first;
}

list_element *list_next(list_element *element) {

	return element->next;
}

void list_push_back(list *container, list_element *element){

    if( list_empty(container) ) {

    	container->first = element;
    	container->last  = element;

    } else {

    	container->last->next = element;
    	container->last = element;
    }

    element->next = 0;
}

list_element *list_pop_front(list *container) {

     list_element *element = container->first;
     container->first = container->first->next;

     return element;
}


/*  end of library code       */
/*  start of main application */

typedef struct {
	/* data */
    list_element header;
    int value;

} apple;

int main()
{
	list apples;

	apple *a = (apple *) malloc( sizeof(apple) );
	apple *b = (apple *) malloc( sizeof(apple) );
	apple *c = (apple *) malloc( sizeof(apple) );

    a->value = 1;
    b->value = 2;
    c->value = 3;
    
    list_init( &apples );

    list_push_back(&apples, &a->header);
    list_push_back(&apples, &b->header);
    list_push_back(&apples, &c->header);

    for(a = (apple *) list_begin( &apples ); a ; a = (apple *) list_next( &a->header) )  {
    	 printf("%d\n", a->value);
    }
      
     while( !list_empty(&apples)) {
     	 a = (apple *) list_pop_front(&apples);
     	 free(a);
     }

   

	return 0;
}