#ifndef  __LINKSTACK_H_

#define __LINKSTACK_H_

#define bool int

#define true 1

#define false 0

typedef int KeyType;

typedef struct lstack

{

    KeyType key;

    struct lstack * top;

}Stack;

Stack*CreateStack();

int IsEmpty();

bool Push();

bool Pop();

Stack*getTopNode();

KeyType getTop();

void Clear();

void Destroy();

#endif

/* linkstack.c */

#include <stdio.h>

#include <stdlib.h>

#include "linkstack.h"

Stack*CreateStack(void)

{

    Stack*s;

    s = (Stack*)malloc(sizeof(Stack));

    s->top = NULL;

    return s;

}

int IsEmpty(Stack*s)

{

    return s->top == NULL;

}

bool Push(Stack*s, KeyType Data)

{

    Stack*p;

    if((p = (Stack*)malloc(sizeof(Stack))) == NULL)

        return false;

    p->key = Data;

    p->top = s->top;

    s->top = p;

    return true;

}

bool Pop(Stack*s)

{

    Stack*p;

    if(IsEmpty(s))

        return false;

    p = s->top;

    s->top = s->top->top;

    free(p);

    p = NULL;

    return true;

}

Stack*getTopNode(Stack*s)

{

    return s->top;

}

KeyType getTop(Stack*s)

{

    return getTopNode(s)->key;

}

void Clear(Stack*s)

{

    while(!IsEmpty(s))

        Pop(s);

}

void Destroy(Stack*s)

{

    if(s != NULL)

    {

        Clear(s);

        if(s != NULL)

            free(s);

        s = NULL;

    }

}