C语言实现动态栈

#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>
 
// 每一个节点的数据类型
typedef struct Node
{
    int data;
    struct Node * pNext;
}NODE, * PNODE; // NODE等价 struct Node   PNODE等价于 struct Node *
 
// 栈
typedef struct Stack
{
    PNODE pTop;
    PNODE pBottom;
}STACK, * PSTACK;
 
void init(PSTACK pS);
void push(PSTACK pS, int val);
void traverse(PSTACK pS);
bool pop(PSTACK pS, int * val);
bool empty(PSTACK pS);
void clear(PSTACK pS);
 
// 这是一个动态栈
int main(void) {
    STACK s; // STACK 等价于 stack Stack
 
    init(&s);// 目的是造出一个空栈
    push(&s, 1);
    push(&s, 2);
    push(&s, 3);
    push(&s, 4);
    traverse(&s);
    int val;
    if (pop(&s, &val))
    {
        printf("出栈成功 出栈的元素是%d\n", val);
    } else {
        printf("出栈失败\n");
    }
    traverse(&s);
    clear(&s);
    traverse(&s);
    if (pop(&s, &val))
    {
        printf("出栈成功 出栈的元素是%d\n", val);
    } else {
        printf("出栈失败\n");
    }
    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");
        exit(-1);
    }
    pS->pTop->pNext = NULL; // 初始化头结点为NULL
    pS->pBottom = pS->pTop;
}
 
void push(PSTACK pS, int val) {
    PNODE pNew = (PNODE)malloc(sizeof(NODE));
    pNew->data = val; // 填充新数据
    pNew->pNext = pS->pTop; // 追加结果
    pS->pTop = pNew;// 更新top
}
 
void traverse(PSTACK pS) {
    PNODE p = pS->pTop;
    printf("开始打印\n");
    while (p != pS->pBottom)
    {
        printf("%d ", p->data);
        p = p->pNext;
    }
    printf("结束打印\n");
}
 
bool empty(PSTACK pS) {
    if (pS->pTop == pS->pBottom)
    {
        return true;
    }
 
    return false;
    
}
 
bool pop(PSTACK pS, int * val) {
    if (empty(pS))
    {
        return false;
    }
    
    *val = pS->pTop->data;
    PNODE r = pS->pTop;
    pS->pTop = pS->pTop->pNext;
    free(r);
    r = NULL;
 
    return true;
}
 
void clear(PSTACK pS) {
    if (empty(pS))
    {
        return;
    }
 
    PNODE p = pS->pTop;
    PNODE q = NULL;
    while (p != pS->pBottom)
    {
        q = p->pNext;
        free(p);
        p = q;
    }
    pS->pTop = pS->pBottom;
}

运行效果