我正在尝试实现一个堆栈类作为学习练习。这是我的StackNode类,
template <typename T>
class StackNode{
public:
T data_{};
StackNode<T> next_;
StackNode() : data_(nullptr), next_(nullptr){}
StackNode(const T& data_) : data_(data_),next_(nullptr) {}
};
我用这个节点创建一个Stack,这是代码,
template <typename T>
class Stack{
private:
StackNode<T> top_;
std::size_t size_{};
public:
Stack() : top_(nullptr), size_ (0){}
void push(const T& item){
StackNode<T> p{item};
p.next_ = top_;
top_ = p;
}
T pop(){
StackNode<T> p = top_;
top_ = top_.next_;
return p;
}
T peek(){
return top_.data_;
}
};
这是呼叫客户端,
Stack<int> stack{};
stack.push(12);
stack.push(13);
std::cout << stack.peek() << std::endl;
stack.pop();
std::cout << stack.peek() << std::endl;
我收到以下编译错误
In file included from /Users/mstewart/Dropbox/codespace/private/cpp-drive/data-structures/main.cpp:2:
In file included from /Users/mstewart/Dropbox/codespace/private/cpp-drive/data-structures/Stack.hpp:5:
/Users/mstewart/Dropbox/codespace/private/cpp-drive/data-structures/StackNode.h:12:18: error: field has incomplete type 'StackNode<int>'
StackNode<T> next_;
^
/Users/mstewart/Dropbox/codespace/private/cpp-drive/data-structures/Stack.hpp:13:18: note: in instantiation of template class 'StackNode<int>' requested here
StackNode<T> top_;
^
/Users/mstewart/Dropbox/codespace/private/cpp-drive/data-structures/main.cpp:6:16: note: in instantiation of template class 'Stack<int>' requested here
Stack<int> stack{};
^
/Users/mstewart/Dropbox/codespace/private/cpp-drive/data-structures/StackNode.h:9:7: note: definition of 'StackNode<int>' is not complete until the closing '}'
class StackNode{
^
有人可以帮助我理解我做错了什么。我是C ++的新手
“一个类实例不能包含它自己的实例” - 评论部分的Oliver Charlesworth。
As mentioned elsewhere,该类在使用时未完全定义(请参阅编译器错误消息中的最后一行),并且存在内存布局问题。
因此,您需要使用指针来管理数组中的项目。对代码进行一次相对简单的调整就是使用std::unique_ptr
(避免使用new
和delete
进行手动内存管理)。
注意所有权语义,其中堆栈拥有顶级节点,该顶级节点拥有下面的节点,等等。您可以使用push函数中的new
和pop函数中的delete
手动使用原始指针来模拟它。