数据结构第三章实验2.实现链栈的各种基本运算

#include <stdio.h>
#include <malloc.h>
typedef char ElemType;
typedef struct linknode
{
ElemType data;              //数据域
struct linknode *next;      //指针域
} LiStack;
void InitStack(LiStack *&s)     //初始化栈s
{   s=(LiStack *)malloc(sizeof(LiStack));
s->next=NULL;
}
void DestroyStack(LiStack *&s)  //销毁栈
{   LiStack *p=s,*q=s->next;
while (q!=NULL)
{   free(p);
p=q;
q=p->next;
}
free(p);    //此时p指向尾节点,释放其空间
}
bool StackEmpty(LiStack *s) //判断栈是否为空
{
return(s->next==NULL);
}
void Push(LiStack *&s,ElemType e)   //进栈
{   LiStack *p;
p=(LiStack *)malloc(sizeof(LiStack));
p->data=e;              //新建元素e对应的节点*p
p->next=s->next;        //插入*p节点作为开始节点
s->next=p;
}
bool Pop(LiStack *&s,ElemType &e)   //出栈
{   LiStack *p;
if (s->next==NULL)      //栈空的情况
return false;
p=s->next;              //p指向开始节点
e=p->data;
s->next=p->next;        //删除*p节点
free(p);                //释放*p节点
return true;
}
bool GetTop(LiStack *s,ElemType &e) //取栈顶元素
{   if (s->next==NULL)      //栈空的情况
return false;
e=s->next->data;
return true;
}
extern void InitStack(LiStack *&s);
extern void DestroyStack(LiStack *&s);
extern bool StackEmpty(LiStack *s);
extern void Push(LiStack *&s,ElemType e);
extern bool Pop(LiStack *&s,ElemType &e);
extern bool GetTop(LiStack *s,ElemType &e);
int  main()
{
ElemType e;
LiStack *s;
printf("栈s的基本运算如下:\n");
printf("  (1)初始化栈s\n");
InitStack(s);
printf("  (2)栈为%s\n",(StackEmpty(s)?"空":"非空"));
printf("  (3)依次进栈元素a,b,c,d,e\n");
Push(s,'a');
Push(s,'b');
Push(s,'c');
Push(s,'d');
Push(s,'e');
printf("  (4)栈为%s\n",(StackEmpty(s)?"空":"非空"));
printf("  (5)出栈序列:");
while (!StackEmpty(s))
{
Pop(s,e);
printf("%c ",e);
}
printf("\n");
printf("  (6)栈为%s\n",(StackEmpty(s)?"空":"非空"));
printf("  (7)释放栈\n");
DestroyStack(s);
}