Test03-郝斌老师-栈基础程序

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

typedef struct Stack
{
    PNODE pTop;    //栈顶
    PNODE pBotton; //栈底
} STACK, *PSTACK;

void init(PSTACK S);
void push(PSTACK S, int val);
void traverse(PSTACK S);
bool pop(PSTACK S, int *pVal);
bool empty(PSTACK S);
void clear(PSTACK S);

int main()
{
    STACK S; // STACK 等价于 struct Stack
    int val; //出栈元素

    init(&S);
    push(&S, 1); // 压栈
    push(&S, 2);
    push(&S, 3);
    push(&S, 4);
    push(&S, 5);
    push(&S, 6);
    traverse(&S);
    
    
    return 0;
}

void init(PSTACK S)
{
    S->pTop = (PNODE)malloc(sizeof(NODE));
    if (NULL == S->pTop)
    {
        printf("动态内存分配失败！n");
        exit(-1);
    }
    else
    {
        S->pBotton = S->pTop;
        S->pBotton->pNext = NULL; //该节点指针域定义为空
    }
}

void push(PSTACK S, int val)
{
    PNODE pNew = (PNODE)malloc(sizeof(NODE));
    pNew->data = val;
    pNew->pNext = S->pTop; //新节点指针域指向旧栈顶
    S->pTop = pNew;        //将top指向新节点
}

void traverse(PSTACK S)
{
    PNODE p = S->pTop;
    while (p != S->pBotton)
    {
        printf("%d ", p->data);
        p = p->pNext;
    }
    printf("n");
}

bool pop(PSTACK S, int *pVal)
{
    if (empty(S))
    {
        return false;
    }
    else
    {
        PNODE r = S->pTop;
        *pVal = r->data;
        S->pTop = r->pNext;
        free(r);
        r = NULL;
        return true;
    }
}

bool empty(PSTACK S)
{
    if (S->pBotton == S->pTop)
    {
        return true; //栈为空
    }
    else
    {
        return false;
    }
}

void clear(PSTACK S)
{
    PNODE p = S->pTop;
    PNODE q = NULL; // p的下一个元素
    while (p != S->pBotton)
    {
        q = p->pNext;
        free(p);
        p = q;
    }
    S->pTop = S->pBotton;
}