动态栈

//动态栈
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>

typedef struct Node
{
    int data;
    struct Node * pNext;
}NODE,*PNODE;

typedef struct stack
{
    PNODE pTop;
    PNODE pBottom;
}STACK,* PSTACK;

void init(PSTACK);          //初始化动态栈
void push(PSTACK,int);      //进栈
void traverse(PSTACK);      //遍历栈
bool empty(PSTACK);         //判断栈是否为空
bool pop(PSTACK,int *);     //出栈
void clear(PSTACK);         //清空栈释放内存

int main()
{
    STACK S;
    int val;

    init(&S);
    push(&S,1);
    push(&S,2);
    push(&S,3);
    push(&S,4);
    push(&S,5);
    traverse(&S);
    pop(&S,&val);
    printf("%d\n",val);
    traverse(&S);
    clear(&S);
    traverse(&S);

    return 0;
}

void init(PSTACK pS)
{
    pS->pTop = (PNODE)malloc(sizeof(NODE));
    if(NULL == pS->pTop)
    {
        printf("动态内存分配失败！\n");
    }
    else
    {
       pS->pBottom = pS->pTop;
       pS->pBottom->pNext = NULL;
    }
}

void push(PSTACK pS,int val)
{
    PNODE pNew = (PNODE)malloc(sizeof(NODE));

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

void traverse(PSTACK pS)
{
    PNODE p = pS->pTop;
    while(p != pS->pBottom)
    {
        printf("%d  ",p->data);
        p = p->pNext;
    }
    printf("\n");
    return;
}

bool empty(PSTACK pS)
{
    if(pS->pTop == pS->pBottom)
        return true;
    else
        return false;
}

bool pop(PSTACK pS,int * pVal)
{
    if(empty(pS))
        return false;
    else
    {
        PNODE r = pS->pTop;
        *pVal= r->data;
        pS->pTop = r->pNext;
        free(r);
        r = NULL;
        return true;
    }
}

void clear(PSTACK pS)
{
    if(empty(pS))
        return;
    else
    {
        PNODE p = pS->pTop;
        PNODE q = pS->pBottom;

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