栈的基本操作

/*
  对栈实现初始化，插入栈顶元素，删除栈顶元素，遍历栈，清空栈等基本操作
  */
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>

//宏定义判断正误
#define true 1
#define false 0

//其实就是结构体类似于链表
typedef struct _Node
{
    int data;
    struct _Node *pNext;
}NODE, *PNODE;


//声明两个节点分别是栈顶与栈底
typedef struct Stack
{
    PNODE pTop;
    PNODE pBottom;
}STACK, *PSTACK;


//初始化栈
void init(PSTACK pS);

//入栈操作
void push(PSTACK pS, int val);

//遍历栈
void traverse(PSTACK pS);


//出栈操作
int pop(PSTACK pS , int *val);

//统计栈的大小
int statistic(PSTACK pS);

//清空栈
void clear(PSTACK pS);

//判断栈是否为空
int empty(PSTACK pS);

int main(void)
{
    STACK S ;//建立一个栈，相当于建立一个链表一样

    int val;//生命一些可用值
    int i;//声明

    init(&S);

    push(&S,1);
    push(&S,2);
    push(&S,3);
    push(&S,4);
    push(&S,5);
    push(&S,6);

    traverse(&S);

    int j = statistic(&S);
    printf("the value is :%d\n ",j);

    if(pop(&S ,&val))
    {
        printf("traverse ok ,the elements out is:%d\n",val);
    }
    else
    {
        printf("elements out failed!\n");
    }
    traverse(&S);
    j = statistic(&S);
    printf("the value is  :%d\n",j);

    clear(&S);

    printf("stack is over!\n");
    traverse(&S);


    return 0 ;
}

//栈的初始化
void init(PSTACK pS)
{
    pS -> pTop = (PNODE)malloc(sizeof(NODE));

    if(NULL == pS -> pTop)
    {
        printf("malloc failed!\n");
        exit(-1);
    }
    else
    {
        pS -> pBottom = pS -> pTop;
        pS -> pTop -> pNext = NULL;
    }

    return ;
}

//插入元素到栈顶
void push(PSTACK pS , int val)
{
    PNODE pNew = (PNODE)malloc(sizeof(NODE));

    pNew -> data = val;
    pNew -> pNext = pS -> pTop;
    pS -> pTop = pNew;

    return ;
}

//遍历栈S
void traverse(PSTACK pS)
{
    PNODE p = pS -> pTop;

    printf("stack elements is:  ");
    while(p != pS -> pBottom)
    {
        printf("%d\t", p -> data);
        p = p -> pNext;
    }

    printf("\n");
    return ;
}

//判断栈是否为空
int empty(PSTACK pS)
{
    if(pS -> pTop == pS -> pBottom)
    {
        return true;
    }
    else
        return false;
}

//删除栈顶元素并将其值赋给*val
int pop(PSTACK pS , int *val)
{
    if(empty(pS))
    {
        return false;
    }
    else
    {
        PNODE r = pS -> pTop;
        *val = r -> data;
        pS -> pTop = r -> pNext;
        free(r);
        r = NULL;
    }
}

//清空栈S
void clear(PSTACK pS)
{
    if(empty(pS))
    {
        return;
    }
    else
    {
        PNODE p = pS -> pTop;
        PNODE q = NULL;

        while(p != pS -> pBottom)
        {
            q = p -> pNext;
            free(p);
            p = q ;
        }

        pS -> pTop = pS -> pBottom;

        return;
    }
}

int statistic(PSTACK pS)
{
    int t_length = 0;
    PNODE p = pS -> pTop;
    if(pS->pBottom == pS->pTop)
    {
        return 0;
    }
    printf("statistic elements start:  ");
    while(p != pS -> pBottom)
    {
        //printf("%d\t", p -> data);
        p = p -> pNext;
        t_length++;
    }
    return t_length;
}