栈的C++实现（指针）——创建-push-pop-top-清空栈-处理栈

今天学习了栈的C++实现，跟单链表很像：

push相当于单链表在第一个位置插入元素；

pop相当于单链表在第一个位置删除元素；

1、空栈检查

int stack::isEmpty(Stack *S)
{
    return S->next == NULL;
}

2、创建一个空栈

stack::Stack *stack::createStack()
{
    Stack *S;
    S = (Stack*)new(Stack);
    //栈空间满后，溢出 
    if (S == NULL)
        cout << "Out of space! " << '
';
    S->next = NULL;
    makeEmpty(S);
    return S;
}

空栈只有头结点，第9行表示若不为空栈则删除除头结点以外的所有结点。

3、清空栈（保留头结点）

void stack::makeEmpty(Stack *S)
{
    if (isEmpty(S))
        cout << "Donnot need to makeEmpty!" << '
';
    else
        while (!isEmpty(S))
            pop(S);
}

4、push操作

stack::Stack *stack::push(int x, Stack *S)
{
    Stack *tem;
    tem = (Stack*)new(Stack);
    if (tem == NULL)
    {
        cout << "Out of space! " << '
';
    }
    else
    {
        cout << "please input the data to push: " << '
';

        scanf_s("%d",&x);

        tem->Data = x;
        tem->next = S->next;
        S->next = tem;
        return S;
    }
}

5、top操作

int stack::top(Stack *S)
{
    if (isEmpty(S))
    {
        cout << "Empty stack! " << '
';
        return -1;
    }
    else
        return S->next->Data;
}

6、pop操作（释放第一个结点后，显示该结点的数据元素）

stack::Stack *stack::pop(Stack *S)
{
    Stack *p;
    p = NULL;
    if (isEmpty(S))
        cout << "Empty stack! " << '
';
    else
    {
        p = S->next;
        cout << "the Data be poped is : " << p->Data << endl;
        S->next = p->next;
        free(p);
        return S;
    }
}

7、处理栈（删除包括头结点）

void stack::disposeStack(Stack *S)
{
    if (S == NULL)
        cout << "Donnot need to disposeStack! " << '
';
    while (!isEmpty(S))
        pop(S);
    free(S);
}

8、主函数

int main()
{
    cout << '
' << "***************************************" << '
' << '
';
    cout << "Welcome to the stack world! " << '
';
    cout << '
' << "***************************************" << '
' << '
';

    int i = 1;
    int j = 0;
    int topElement = 0;
    stack *a = new stack;
    stack::Stack *S = NULL;
    int x = 0;
    while (i)
    {
        cout << '
' << "***************************************" << '
';
        cout << " 0 : end the stack " << '
';
        cout << " 1 : creat a stack " << '
';
        cout << " 2 : display the top element of stack  " << '
';
        cout << " 3 : push a node in the stack  " << '
';
        cout << " 4 : pop a node from the stack  " << '
';
        cout << "***************************************" << '
';
        cout << "Please input the function your want with the number above : " << '
';
        scanf_s("%d", &j);

        switch (j)
        {
        case 1:
            cout << "CreatStack now begin : ";
            S = a->createStack();
            break;
        case 2:
            topElement = a->top(S);
            cout << "The top element of stack is : " << topElement;
            break;
        case 3:
            cout << "push now begin : ";
            S = a->push(x, S);
            break;
        case 4:
            cout << "pop now begin : ";
            S = a->pop(S);
            break;
        default:
            cout << "End the stack. ";
            a->disposeStack(S);
            i = 0;
            break;
        }

    }
}

运行结果：