栈结构实现

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


typedef struct       //定义栈模型
{
    PNODE TOP;
   PNODE BUTTOM;
}*PSTACK,STACK;


栈定义的模型
初始化方法，压入栈的方法，出栈的方法，遍历的方法，
*/
//初始化栈的操作
void init_stack(PSTACK);
//压入栈
void push_stack(PSTACK, int);
//出栈
void pop_stack(PSTACK, int*);
//遍历
void traverse(PSTACK);
//是否为空
bool empty(PSTACK);
//clear;
void clear(PSTACK);

实现上述栈的函数
*/
//初始化
void init_stack(PSTACK phead){
  PNODE stack = (PNODE)malloc(sizeof(NODE));
  if (stack == NULL){
      printf("创建失败！");
       return ;
    }
    phead->BUTTOM = stack;
  phead->TOP = phead->BUTTOM;
    phead->TOP->next = NULL;

}
//入栈
void push_stack(PSTACK phead, int val){
    PNODE pnew = (PNODE)malloc(sizeof(NODE));
 pnew->data = val;
 pnew->next = phead->TOP;
   phead->TOP = pnew;
}
//出栈
void pop_stack(PSTACK phead, int *val){
   if (empty(phead))
   {
        return;
 }
    PNODE p = phead->TOP;
 *val = p->data;
   phead->TOP = p->next;
  free(p);
   p = NULL;
}
//遍历
void traverse(PSTACK phead){
  PNODE p = phead->TOP;
 while (phead->BUTTOM!=p)
 {
        printf("%d", p->data);
      p = p->next;
  }
}
//是否为空
bool empty(PSTACK phead){
    if (phead->BUTTOM == phead->TOP)
      return true;
   return false;
}
//clear
void clear(PSTACK phead){
 if (empty(phead))
       return;
 PNODE p = phead->TOP;
 while (p != phead->BUTTOM)
   {
        phead->TOP = p->next;
      free(p);
       p = phead->TOP;
   }
}

void main(){
  STACK stack;
   int val;
    init_stack(&stack);   //初始化
   if (empty(&stack))  //
       printf("空stackn");
 push_stack(&stack, 1);//push
  push_stack(&stack, 2);
 push_stack(&stack, 3);
 traverse(&stack);   //遍历
  pop_stack(&stack, &val);
   clear(&stack);  //clear
   pop_stack(&stack, &val);
   printf("%d", val);
 pop_stack(&stack, &val);
   pop_stack(&stack,&val);   //pop
   system("pause");
}