c模擬鏈表操作,筆記

#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
//動態棧，由鏈表實現 ,上面節點指向下面一個節點 
//結構體：節點（表示一個元素） 
typedef struct Node
{
 int data;
 struct Node * pNext;
}NODE,*PNODE;

//結構體：棧，棧頂節點的指針，棧底節點指針(棧底指針指向棧底節點的下一個存儲空間,因爲是初始化的時候分配的空間，此時還沒有插入節點)。 
typedef struct Stack
{
 PNODE pTop;
 PNODE pButtom;
        
} STACK,*PSTACK;
//爲棧分配內存 
void init(PSTACK pStack); 
//壓棧
void push(PSTACK pStack,int val);
//遍歷 
void traverse(PSTACK pStack);
//彈棧,把出棧的節點的數據存入給定的變量中(給地址) 
bool pop(PSTACK pStack,int * val); 
int main(void)
{
 //初始化
 STACK stack;
 init(&stack); 
 //壓棧
  push(&stack,1);
   push(&stack,2);
    push(&stack,3);
     push(&stack,4);
     //遍歷
    traverse(&stack); 
    //彈棧
    int a = 0;
    pop(&stack,&a); 
    printf("\n出棧的元素是:%d\n",a);
    //遍歷
    traverse(&stack); 
     getchar();
 return 0;    
}
//初始化棧 
void init(PSTACK pStack)
{
     //爲節點分配內存 
 pStack->pTop = (PNODE)malloc(sizeof(NODE));
 if(pStack->pTop == NULL)
 {
  printf("動態內存分配失敗!\n");
  exit(-1);
 }else
 {
     //棧頂指針和棧底指針相等 ,都指向初始節點 
  pStack->pButtom = pStack->pTop;  
  pStack->pTop->pNext = NULL;  //初始節點的下個節點爲NULL 
 }
}
//壓棧 
void push(PSTACK pStack,int val)
{
      //創建一個節點  
      PNODE pNewNode= (PNODE)malloc(sizeof(NODE));
      pNewNode->data = val;//數據域賦值 
      pNewNode->pNext = NULL;//指針域爲空(棧頂) 
      pNewNode->pNext = pStack->pTop;//新加入的節點的下一個節點指向原來的棧頂節點 
      pStack->pTop = pNewNode;//棧頂指針指向新壓入的節點
      return; 
}
//遍歷
void traverse(PSTACK pStack)
{
      PNODE pNode = pStack->pTop;
      while(pNode != pStack->pButtom)
      {
       printf("%d\t",pNode->data);
       pNode =  pNode->pNext;      
      }
} 
//彈棧 
bool pop(PSTACK pStack,int * val)
{    
     if(pStack->pTop == pStack->pButtom)
    {
     return   false;              
    }
    *val = pStack->pTop->data; 
    PNODE r= pStack->pTop;//記錄棧頂節點 
    pStack->pTop = pStack->pTop->pNext;
    free(r); 
    r=NULL;//釋放原來棧頂節點的空間 
    return true;
   
}