链栈的实现

#include <stdio.h>
#include<stdlib.h>
//链栈的实现
typedef struct Node{
	int data;
	struct Node *next;
}Node;
Node *top;
Node *in(){
	return NULL;
	
}
int empty(Node *top){
	if(!top) return 1;
	else return 0;
}
Node *push(Node *top,int x){
	Node *s;
	s=(Node*)malloc(sizeof(Node));
	s->data=x;
	s->next=top;
	top=s;return top;
}
Node *pop(Node *top){
	Node *p;
	p=top;
	top=top->next;
	free(p);
	return top;
}
int to(Node *top){
	
	return top->data;
	
}
int main(){ 
top=in(); 
top=push(top,1); 
top=push(top,2); 
top=push(top,3);

printf("栈顶元素为：%d\n",to(top));
top=pop(top);
printf("移除栈顶元素后，栈顶元素为：%d\n",to(top));

return 0;
}