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/* Standard C */
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
/* Project */
#include "util.h"
typedef int T;
struct stack_item {
struct stack_item *next;
T data;
};
struct stack {
struct stack_item *head;
};
void
stack_init(struct stack *stack)
{
stack->head = NULL;
}
void
stack_push(struct stack *stack, T data)
{
struct stack_item *new_item;
if ( (new_item = malloc(sizeof(*new_item))) != NULL ) {
new_item->data = data;
new_item->next = stack->head;
stack->head = new_item;
}
else
ERROR("out of memory");
}
bool
stack_pop(struct stack *stack, T *data)
{
if ( stack->head != NULL ) {
struct stack_item *next = stack->head->next;
if ( data != NULL ) {
*data = stack->head->data;
}
free(stack->head);
stack->head = next;
return true;
}
else
return false;
}
bool
stack_empty(struct stack *stack)
{
return stack->head == NULL;
}
void
stack_free(struct stack *stack)
{
struct stack_item *item, *next;
for ( item = stack->head; item; item = next ) {
next = item->next;
free(item);
}
}
int
main()
{
struct stack stack[1];
stack_init(stack);
for ( int i = 0; i != 10; ++i )
stack_push(stack, i);
/*
while ( !stack_empty(stack) ) {
int i;
if ( stack_pop(stack, &i) )
printf("%d\n", i);
else
ERROR("this shouldn't happen!");
}
*/
stack_free(stack);
return EXIT_SUCCESS;
}
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