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

1 int stack::isEmpty(Stack *S)
2 {
3     return S->next == NULL;
4 }

2、创建一个空栈

 1 stack::Stack *stack::createStack()
 2 {
 3     Stack *S;
 4     S = (Stack*)new(Stack);
 5     //栈空间满后，溢出
 6     if (S == NULL)
 7         cout << "Out of space! " << ‘\n‘;
 8     S->next = NULL;
 9     makeEmpty(S);
10     return S;
11 }

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）

1 void stack::makeEmpty(Stack *S)
2 {
3     if (isEmpty(S))
4         cout << "Donnot need to makeEmpty!" << ‘\n‘;
5     else
6         while (!isEmpty(S))
7             pop(S);
8 }

4、push操作

 1 stack::Stack *stack::push(int x, Stack *S)
 2 {
 3     Stack *tem;
 4     tem = (Stack*)new(Stack);
 5     if (tem == NULL)
 6     {
 7         cout << "Out of space! " << ‘\n‘;
 8     }
 9     else
10     {
11         cout << "please input the data to push: " << ‘\n‘;
12
13         scanf_s("%d",&x);
14
15         tem->Data = x;
16         tem->next = S->next;
17         S->next = tem;
18         return S;
19     }
20 }

5、top操作

 1 int stack::top(Stack *S)
 2 {
 3     if (isEmpty(S))
 4     {
 5         cout << "Empty stack! " << ‘\n‘;
 6         return -1;
 7     }
 8     else
 9         return S->next->Data;
10 }

6、pop操作（释放第一个结点后，显示该结点的数据元素）

 1 stack::Stack *stack::pop(Stack *S)
 2 {
 3     Stack *p;
 4     p = NULL;
 5     if (isEmpty(S))
 6         cout << "Empty stack! " << ‘\n‘;
 7     else
 8     {
 9         p = S->next;
10         cout << "the Data be poped is : " << p->Data << endl;
11         S->next = p->next;
12         free(p);
13         return S;
14     }
15 }

7、处理栈（删除包括头结点）

1 void stack::disposeStack(Stack *S)
2 {
3     if (S == NULL)
4         cout << "Donnot need to disposeStack! " << ‘\n‘;
5     while (!isEmpty(S))
6         pop(S);
7     free(S);
8 }

8、主函数

 1 int main()
 2 {
 3     cout << ‘\n‘ << "***************************************" << ‘\n‘ << ‘\n‘;
 4     cout << "Welcome to the stack world! " << ‘\n‘;
 5     cout << ‘\n‘ << "***************************************" << ‘\n‘ << ‘\n‘;
 6
 7     int i = 1;
 8     int j = 0;
 9     int topElement = 0;
10     stack *a = new stack;
11     stack::Stack *S = NULL;
12     int x = 0;
13     while (i)
14     {
15         cout << ‘\n‘ << "***************************************" << ‘\n‘;
16         cout << " 0 : end the stack " << ‘\n‘;
17         cout << " 1 : creat a stack " << ‘\n‘;
18         cout << " 2 : display the top element of stack  " << ‘\n‘;
19         cout << " 3 : push a node in the stack  " << ‘\n‘;
20         cout << " 4 : pop a node from the stack  " << ‘\n‘;
21         cout << "***************************************" << ‘\n‘;
22         cout << "Please input the function your want with the number above : " << ‘\n‘;
23         scanf_s("%d", &j);
24
25         switch (j)
26         {
27         case 1:
28             cout << "CreatStack now begin : ";
29             S = a->createStack();
30             break;
31         case 2:
32             topElement = a->top(S);
33             cout << "The top element of stack is : " << topElement;
34             break;
35         case 3:
36             cout << "push now begin : ";
37             S = a->push(x, S);
38             break;
39         case 4:
40             cout << "pop now begin : ";
41             S = a->pop(S);
42             break;
43         default:
44             cout << "End the stack. ";
45             a->disposeStack(S);
46             i = 0;
47             break;
48         }
49
50     }
51 }

运行结果：