/*顺序表实现栈的一系列操作*/ 

#include<stdio.h>
#include<stdlib.h> 

#define Stack_Size 50             //设栈中元素个数为50 
#define OK 1
#define ERROR 0

typedef struct                
{
    int elem[Stack_Size];          //用来存放栈中元素的一维数组 
    int top;                       //用来存放栈顶元素的下标，top为 -1 表示空栈 
}SeqStack;

/**********************各个子函数的定义*********************/
int initStack(SeqStack *S);         //初始化顺序栈 
void push(SeqStack *S,int n);          //顺序栈进栈运算 
void pop(SeqStack *S);                //顺序栈出栈运算 
int getTop(SeqStack *S,int *s);     //读取栈顶元素 
 
int main()
{
    SeqStack *S;
    int choice;
    while(true)
    {
        printf("*****************Please enter your choice*****************\n\n");
        printf("                choice 1：Stack initialization\n");
        printf("                choice 2：Into the stack\n");
        printf("                choice 3：Out of the stack\n");
        printf("                choice 4：Read the stack elements\n");
        printf("                choice 0：exit\n\n");
         scanf("%d",&choice);
        switch(choice)
        {
            case 1:
                (initStack(S)==1)?printf("initStck success.\n"):printf("initStack ERROR\n");
                break;
            case 2:
                int n;
                printf("Please enter the number into the stack elements：");
                scanf("%d",&n);
                push(S,n);
                break;
            case 3:
                pop(S);
                break;
            case 4:
                int* s;
                (getTop(S,s)==1)? printf("栈顶元素是：%d.\n",*s):printf("An empty stack error!!!!\n"); //三目运算符
                break;        
            case 0:
                exit(0);
                break;
            default:
                printf("ERROR！！\n");
                exit(0);
                break;
        }
    }
    return 0;
} 

/**********************各个子函数功能的实现*********************/
int initStack(SeqStack *S)    //初始化顺序栈 
{         
    if(S!=NULL)
    {
        S->top=-1;             //置为空栈 
        return OK;
    }
    else return ERROR;        //内存空间不足 
}
void push(SeqStack *S,int n)  //进栈 ，将元素压入栈中 
{   
    int n1,n2;
    if(((S->top)+n)<=Stack_Size-1)   //压入栈中的元素不能超过栈的最大存储 
    {  
        printf("Please enter into the stack elements in turn:\n");  
        for(n1=0;n1<n;n1++)
        {
            scanf("%d",&n2);
            S->top++;                    //移动栈顶指针 
            S->elem[S->top]=n2;
        }
        printf("%d个元素依次进栈成功\n",n);
    }
    else
    {                    //栈空间不够 
        printf("ERROR There is insufficient space on the stack.\n");            
    }                 
}
void pop(SeqStack *S)
{     //栈顶元素出栈 
    int a;
    if(S->top==-1)
    {               //栈为空，操作失败 
        printf("An empty stack error!!!!\n");
    }
    else
    {
        a=S->elem[S->top];
        S->top--;
        printf("栈顶元素%d出栈成功.\n",a);  //出栈成功 
    }  

}
int getTop(SeqStack *S,int *s)   //获取栈顶元素 
{    
    if(S->top==-1)
    {               //栈为空，操作失败 
        return ERROR;
    }
    else
    {
        *s=S->elem[S->top];   //读取栈顶元素成功 
        return OK;
    }
}