C语言实现栈的基本操作

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

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

typedef struct Stack
{
PNODE pTop;
PNODE pBottom;
}STACK, * PSTACK;     //PSTACK等价于struct STACK *

void init(PSTACK); //初始化栈
void push(PSTACK, int );  //压栈
void traverse(PSTACK);    //遍历
bool pop(PSTACK pS,int * pVal);   //出栈
void clear(PSTACK pS);    //清空栈

int main(void)
{
STACK S;  //STACK等价于struct Stack
int val;
init(&S);  //造出空栈

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

traverse(&S); //遍历输出
/*
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");
}
*/
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");
exit(-1);
}
else
{
pS->pBottom = pS->pTop;
pS->pTop->pNext = NULL;
}
}

void push(PSTACK pS, int val)
{
PNODE pNew = (PNODE)malloc(sizeof(NODE));  //创建新的节点
pNew->data = val;  //将val的值赋给新节点的数据域
pNew->pNext = pS->pTop; //将新节点的指针域指向下一个节点.pS->Top不能改写成pS->Bottom
pS->pTop = pNew; //pTop指向新节点
return;
}

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;
}
}

//清空栈
void clear(PSTACK pS)
{
if(empty(pS))        //如果
{
return;
}
else
{
PNODE p = pS->pTop;  //定义元素p指向栈顶元素
PNODE q = NULL；     //定义元素q，初始值为空

while(p !=pS->pBottom)    //如果栈不为空
{
q = p->pNext;        //q指向p的下一个元素
free(p);            //释放p所指向的栈顶元素
p = q;               //将q所指向的元素赋给p
}
pS->pTop = pS->pBottom;
}
}