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! " << '\n';
     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!" << '\n';
     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! " << '\n';
     }
     else
     {
         cout << "please input the data to push: " << '\n';

         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! " << '\n';
         return -;
     }
     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! " << '\n';
     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! " << '\n';
     while (!isEmpty(S))
         pop(S);
     free(S);
 }

8、主函数

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

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

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

     }
 }

运行结果：