数据结构-链栈的基本操作

//链栈的基本操作
#include<iostream>
using namespace std;
typedef char elemtype;
typedef struct linknode
{
	elemtype data;
	struct linknode*next;
}linkstack;
void gettop(linkstack*&s)//取栈顶元素
{
	if(s->next==NULL)
		cout<<"error"<<endl;
	char e=s->next->data;
	cout<<"栈顶元素:"<<e<<endl;
}
void popall(linkstack*&s)//全部元素出栈
{
	linkstack*p;
	if(s->next==NULL)
		cout<<"error!"<<endl;
	while(s->next!=NULL)
	{
	p=s->next;
	char e=p->data;
	s->next=p->next;
	free(p);
	cout<<e<<"出栈"<<endl;
	}
}
void pop(linkstack*&s)//出栈
{
	linkstack*p;
	if(s->next==NULL)
		cout<<"error!"<<endl;
	p=s->next;
	char e=p->data;
	s->next=p->next;
	free(p);
	cout<<e<<"出栈"<<endl;
}
void push(linkstack*&s,elemtype e)//进栈
{
	linkstack*p;
	p=(linkstack*)malloc(sizeof(linkstack));
	p->data=e;
	p->next=s->next;
	s->next=p;
	cout<<e<<"进栈"<<endl;
}
void empty(linkstack*s)//判断栈是否为空
{
	if(s->next==NULL)
		cout<<"空!"<<endl;
	else
		cout<<"非空!"<<endl;
}
void destroy(linkstack*&s)//销毁栈
{
	linkstack*pre=s,*p=s->next;
	while(p!=NULL)
	{
		free(pre);
		pre=p;
		p=pre->next;
	}
	free(pre);
}
void init(linkstack*&s)//初始化栈
{
	s=(linkstack*)malloc(sizeof(linkstack));
	s->next=NULL;
}
int main()
{
	linkstack*s;
	init(s);
	empty(s);
	push(s,'a');
	push(s,'b');
	push(s,'c');
	push(s,'d');
	push(s,'e');
	empty(s);
	gettop(s);
	popall(s);
	empty(s);
	destroy(s);
	return 0;
}