//栈的链式存储表示(在栈中，top指向栈顶元素)
#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>

typedef struct SqStack{

    struct SqStack *next;
    int data;

}Node;

struct SqStack *top;//栈顶指针

//初始化栈
void InitStack(){
    
    top = NULL;
    
}

//判断栈是否为空
bool EmptyStack(){

    if(top==NULL)
        return true;
    else
        return false;
}

//返回栈中的元素个数
int StackLength(){

  Node *s;
  int num = 0;
  s = top;
  while(s){

    num++;
    s = s->next;
  }

  return num;

}

//获取栈顶元素
int GetTop(){
  
    return top->data;
}

//入栈
void Push(int value){
    
    Node *s = (Node *)malloc(sizeof(Node));
    s->data = value;
    s->next = top;
    top = s;
 
}

//出栈
bool Pop(int *e){
    
    if(!EmptyStack()){

        Node *s;
        s = top;
        *e = top->data;
        top = top->next;
        free(s);

    }else{
        
        return false;
    }
    
    return true;
}

//遍历栈
void StackTraverse(){
    
    Node* s = top;

    while(s){
        printf("%d ",s->data);
        s = s->next;
    }
    printf("\n");
}

int main()
{

    int i=1;
    int e;

    InitStack();//构造一个空栈  

    for(i=1;i<=13;i++){

        Push(i);//进行入栈
    }

    printf("遍历栈元素如下：\n");
    StackTraverse();//遍历栈
    
    int len = StackLength();

    printf("出栈操作元素如下：\n");
    for(i=1;i<=len;i++){//不要把StackLength()放置此处，会出现逻辑错误。

        if(Pop(&e))
        {
            printf("%d ",e);

        }else{

            printf("出栈失败\n");
        }

    }
    printf("\n");
    
    //再次进行入栈，不然会影响后续测试
    for(i=1;i<=13;i++){

        Push(i);
    }

    //获取栈顶元素
    printf("栈顶元素：%d\n",GetTop());

    return 0;
}