栈的相关操作

# include <stdio.h>
# include <malloc.h>
# include <stdlib.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);
void push(PSTACK, int );
void traverse(PSTACK);
bool pop(PSTACK, int *);
void clear(PSTACK pS);int main(void)
{STACK S;  //STACK 等价于 struct Stackint val;init(&S);  //目的是造出一个空栈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
    clear(&S);//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");}traverse(&S); //遍历输出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; //pS->Bottom->pNext = NULL;
    }
}void push(PSTACK pS, int val)
{PNODE pNew = (PNODE)malloc(sizeof(NODE));pNew->data = val;pNew->pNext = pS->pTop; //pS->Top不能改成pS->BottompS->pTop = pNew;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;elsereturn false;
}//把pS所指向的栈出栈一次，并把出栈的元素存入pVal形参所指向的变量中，如果出栈失败，返回false,否则返回true
bool pop(PSTACK pS, int * pVal)
{if ( empty(pS) ) //pS本身存放的就是S的地址
    {return false;}else{PNODE r = pS->pTop;*pVal = r->data;pS->pTop = r->pNext;free(r);r = NULL;return true;}
}//clear清空
void clear(PSTACK pS)
{if (empty(pS)){return;}else{PNODE p = pS->pTop;PNODE q = NULL;while (p != pS->pBottom){q = p->pNext;free(p);p = q;}pS->pTop = pS->pBottom;}
}