数据结构-----栈

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

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

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

void init(PSTACK pS);

bool push(PSTACK , int);
void traverse(PSTACK );
bool pop(PSTACK,int*);
void clear(PSTACK);

void init(PSTACK pS)
{
    PNODE p = (PNODE)malloc(sizeof(NODE));
    if(p ==NULL)
    {
        printf("申请动态内存失败！
");
        exit(-1);
    }
    p->pNext = NULL;
    pS->pBottom = p;
    pS->pTop = p;

}
bool push(PSTACK pS , int val)
{
    PNODE p = (PNODE)malloc(sizeof(NODE));
    if(NULL==p)
    {
        printf("申请动态内存失败！
");
        exit(-1);
    }
    p->data = val;
    p->pNext = pS->pTop;
    pS->pTop = p;
    return true;
}
bool pop(PSTACK pS,int* val)
{
    if(pS->pTop == pS->pBottom)
        return false;
    PNODE p = pS->pTop;
    *val = p->data;
    pS->pTop = p->pNext;
    free(p);
    p =NULL;
    return true;
}

void clear(PSTACK pS)
{
    while(pS->pTop != pS->pBottom)
    {
        pop(pS);
    }
    return;

}

void traverse(PSTACK pS)
{
    PNODE  p = pS->pTop;
    while(p->pNext !=NULL)
    {
        printf("%d
",p->data);
        p = p->pNext;
    }
    return;
}

int main(void)
{
    STACK S;
    int 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);

    pop(&S,&val);
    traverse(&S);
    clear(&S);
    traverse(&S);

    return 0;
}