對棧的一些簡單操做

#include<stdio.h>

#include<stdlib.h>

#include<malloc.h>

struct node

{

int date;

struct node *pnext;

};

struct stack

{

struct node *ptop;

struct node *pbottom;

};

void init(struct stack *p);//棧初始化函數

bool is_empty(struct stack *p);//判斷棧是否爲空函數

bool pop(struct stack *p,int *shu);//出棧函數

void push(struct stack *p ,int shu);//壓棧函數*/

void traverse(struct stack *p);//棧遍歷函數 

void clear(struct stack *p) ;//清空棧函數 

int main()

{    int val;//用來表示出棧的元素 

struct stack s;

init(&s);

push(&s,5);

push(&s,55);

push(&s,545);

push(&s,1258);

traverse(&s);

   if( pop(&s,&val) )

   {

    printf("出棧成功，出棧的元素是：%d\n",val);

   

   }

   else

    {

    printf("出棧失敗！\n");

   }

 if( pop(&s,&val) )

   {

    printf("出棧成功，出棧的元素是：%d\n",val);

   

   }

   else

    {

    printf("出棧失敗！\n");

   }

traverse(&s);

clear(&s);

traverse(&s);

push(&s,1258);

traverse(&s);

return 0;

}

void init(struct stack *p) 

{

p->ptop=(struct node *)malloc(sizeof(struct node));//這個纔要申請分配內存 

if(NULL==p->ptop)

{

printf("內存分配失敗！\n");

exit(-1);

}

else

{

p->pbottom=p->ptop;

      p->ptop->pnext=NULL;//或者p->pbottom->pnext=NULL 

}

return ;

 

}

void traverse(struct stack *p)

{

struct node *ptail=p->ptop;

while(p->pbottom!=ptail)//開始寫錯了，不要寫成NULL！=ptail 

{

printf("%d ",ptail->date);

ptail=ptail->pnext;

}

printf("\n");

return ;

}

bool is_empty(struct stack *p)

{

if(p->ptop==p->pbottom)

return true;

else

return false;

} 

void push(struct stack *p, int shu)

{

struct node *ptail=(struct node *)malloc(sizeof(struct node));

if(NULL==ptail)//這個能夠不用，後面也是 

{

  printf("內存分配失敗！\n");

  exit(0);

  }

 ptail->date=shu;

    ptail->pnext=p->ptop;//空棧時能夠寫ptail->pnext=p->pbottom,因此這點要注意，不能寫成 p->pbottom

  p->ptop=ptail;

 // printf("\n");

  return ;

 

}

bool pop(struct stack *p,int *shu)//出棧 

{

if(is_empty(p))

return false;

else

{

struct node *ptail=(struct node *)malloc(sizeof(struct node));

if(NULL==ptail) 

{

printf("內存分配失敗！\n");

exit(0);

}

ptail=p->ptop;

*shu=ptail->date;

p->ptop=ptail->pnext;

free(ptail);

ptail=NULL;

return true;

}

}

void clear(struct stack *p)

{

if(is_empty(p))

{

printf("棧爲空，不準清空！\n");

}

struct node *ptail=(struct node *)malloc(sizeof(struct node));

if(ptail==NULL)

{

printf("內存分配失敗！\n");

exit(0);

}

ptail=p->ptop;

struct node *qtail=ptail->pnext;

while(ptail!=p->pbottom)//這裏能夠優化 

{   free(ptail);

ptail=qtail;

qtail=ptail->pnext;

}

p->ptop=p->pbottom;

return ;

}