栈的实现—由链表实现

#include
#include

typedef int datatype;

typedef struct _node_
{
 datatype data;
 struct _node_ *next;
} linkstack;

linkstack *CreateEmptyStack_1()
{
 linkstack *s;

 s = (linkstack *)malloc(sizeof(linkstack));
 s->next = NULL;

 return s;
}

void CreateEmptyStack_2(linkstack **s)
{
 *s = (linkstack *)malloc(sizeof(linkstack));
 (*s)->next = NULL;

 return;
}

int EmptyStack(linkstack *s)
{
 return (NULL == s->next);
}

void ClearStack(linkstack *s)
{
 linkstack *p, *q;

 p = s->next;
 while (p != NULL)
 {
  q = p;
  p = p->next;
  free(q);
 }
 s->next = NULL;

 return;
}

void PushStack(linkstack *s, datatype x)
{
 linkstack *p;

 p = (linkstack *)malloc(sizeof(linkstack));
 p->data = x;
 p->next = s->next;
 s->next = p;

 return;
}

datatype PopStack(linkstack *s)
{
 linkstack *q;
 datatype x;

 q = s->next;
 s->next = q->next;
 x = q->data;
 free(q);

 return x;
}

datatype GetTop(linkstack *s)
{
 return s->next->data;
}