项目场景：

命名空间域中VS报错"kv_test": 不是 “K” 的成员.

实际上, 我看了一下kv_test函数确实在K这个命名空间作用域中, 但是却报这个错误…有点懵比~

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问题描述

疑惑很简单, 我这个函数明明在K这个空间域中为啥给我报错呢?

#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;

namespace K
{
	template<class K>
	struct BSTreeNode
	{
		K _val;
		BSTreeNode<K>* _left;
		BSTreeNode<K>* _right;

		struct BSTreeNode(int k = 0)
			:_val(k)
			,_left(nullptr)
			,_right(nullptr)
		{}
	};

	template<class K>
	struct BSTree
	{
		typedef struct BSTreeNode<K> Node;
	private:
		Node* _root = nullptr;
	public:
		bool Push(K x)
		{
			if (_root == nullptr)
			{
				_root = new Node(x);
				return true;
			}

			Node* parent = _root; 
			// 这个地方初始值应该给多少呢? 首先我们已经排除了_root = nullptr的情况, 
			// 换句话说while循环一定会进去
			// 
			Node* cur = _root;
			while (cur)
			{
				if (cur->_val < x)
				{
					parent = cur;
					cur = cur->_right;
				}
				else if (cur->_val > x)
				{
					parent = cur;
					cur = cur->_left;
				}
				else
				{
					//重复~ 
					return false;
				}
			}

			//走到这里, 表示cur走到空了, 然后parent指向要插入位置的父亲. 
			Node* newnode = new Node(x);
			if (parent->_val < x)
			{
				parent->_right = newnode;
			}
			else if(parent->_val > x)
			{
				parent->_left = newnode;
			}
			else
			{
				cout << "未知错误" << endl;
			}

			return true;
		}//Push


		bool Find(K x)
		{
			Node* cur = _root;

			while (cur)
			{
				if (cur->_val == x)
				{
					return true;
				}
				else if (cur->_val < x)
				{
					cur = cur->_right;
				}
				else
				{
					cur = cur->_left;
				}
			}

			return false;
		}//Find

		bool Pop(K x)
		{
			Node* cur = _root;
			Node* parent = _root;

			while (cur)
			{
				if ((cur->_val == 3) && (x == 3)) 
					int b = 10;

				if (cur->_val == x)
				{
					//这个地方我们准备删除了, 因为找到了~ 

					//1.如果cur左为空 -> 让父亲去接管cur的右
					if (cur->_left == nullptr)
					{
						//特殊情况, 假如说删除的就是根呢? 
						if (cur == _root)
						{
							//让根的右成为新的树
							_root = _root->_right;
							delete cur;

							return true;
						}

						//这里需要判断cur是parent的左还是右...
						if (parent->_left == cur)
						{
							parent->_left = cur->_right;
						}
						else
						{
							parent->_right = cur->_right;
						}
						delete cur;
					}//1.如果cur左为空
					//2.如果cur右为空 -> 让父亲去接管cur的左
					else if (cur->_right == nullptr)
					{
						//特殊情况, 假如说删除的就是根呢? 
						if (cur == _root)
						{
							//让根的左成为新的树
							_root = _root->_left;
							delete cur;

							return true;
						}

						//这里需要判断cur是parent的左还是右...
						if (parent->_left == cur)
						{
							parent->_left = cur->_left;
						}
						else
						{
							parent->_right = cur->_left;
						}
						delete cur;
					}//2.如果cur右为空
					//3. 第三种情况, 就是cur左右都有孩子~ 
					else
					{
						//3.1找到右子树中最大的结点
						Node* MinCur = cur->_right;
						Node* MinParent = cur;

						while (MinCur->_left)
						{
							MinParent = MinCur;
							MinCur = MinCur->_left;
						}
						//3.2交换
						swap(MinCur->_val, cur->_val);

						//3.3调整孩子...
						if (MinParent->_left == MinCur)
						{
							MinParent->_left = MinCur->_right;
						}
						else if (MinParent->_right == MinCur)
						{
							MinParent->_right = MinCur->_right;
						}

						//3.4删除
						delete MinCur;
					}//3.cur左右都有孩子~ 

					return true; //表示删除成功~ 
				}
				else if (cur->_val < x)
				{
					parent = cur;
					cur = cur->_right;
				}
				else
				{
					parent = cur;
					cur = cur->_left;
				}
			}

			//如果这个结点压根就不存在, 肯定就不能删除咯~ 包括空树 
			return false;
		}//Pop

		void InOrder()
		{
			_InOrder(_root);
		}

		void _InOrder(Node* node)
		{
			if (node == nullptr)
			{
				cout << "N" << " ";
				return;
			}

			_InOrder(node->_left);
			cout << node->_val << " ";
			_InOrder(node->_right);
		}

	};//BSTree

	void k_test()
	{
		K::BSTree<int> tree;
		tree.Push(1);
		tree.Push(2);
		tree.Push(3);
		tree.Push(4);
		tree.Push(5);
		tree.Push(6);

		cout << tree.Find(1) << endl;
		cout << tree.Find(99) << endl;
		cout << tree.Find(122) << endl;
		cout << tree.Find(2) << endl;

		int a[] = { 8, 3, 1, 10, 6, 4, 7, 14, 13 };
		for (auto& e : a)
		{
			tree.Push(e);
			tree.InOrder();
			cout << endl;
		}

		for (auto& e : a)
		{
			tree.Pop(e);
			cout << "pop: " << e << "  ";
			tree.InOrder();
			cout << endl;
		}
	}
}

namespace KV
{
	template<class K, class V>
	struct BSTreeNode
	{
		K _val;
		V _vue;
		BSTreeNode<K, V>* _left;
		BSTreeNode<K, V>* _right;

		struct BSTreeNode(K k = K(), V v = V())
			:_val(k)
			, _vue(v)
			, _left(nullptr)
			, _right(nullptr)
		{}
	};

	template<class K, class V>
	struct BSTree
	{
		typedef struct BSTreeNode<K, V> Node;
	private:
		Node* _root = nullptr;
	public:
		bool Push(K x, V v)
		{
			if (_root == nullptr)
			{
				_root = new Node(x, v);
				return true;
			}

			Node* parent = _root;
			// 这个地方初始值应该给多少呢? 首先我们已经排除了_root = nullptr的情况, 
			// 换句话说while循环一定会进去
			// 
			Node* cur = _root;
			while (cur)
			{
				if (cur->_val < x)
				{
					parent = cur;
					cur = cur->_right;
				}
				else if (cur->_val > x)
				{
					parent = cur;
					cur = cur->_left;
				}
				else
				{
					//重复~ 
					return false;
				}
			}

			//走到这里, 表示cur走到空了, 然后parent指向要插入位置的父亲. 
			Node* newnode = new Node(x, v);
			if (parent->_val < x)
			{
				parent->_right = newnode;
			}
			else if (parent->_val > x)
			{
				parent->_left = newnode;
			}
			else
			{
				cout << "未知错误" << endl;
			}

			return true;
		}//Push


		Node* Find(K x)
		{
			Node* cur = _root;

			while (cur)
			{
				if (cur->_val == x)
				{
					return cur;
				}
				else if (cur->_val < x)
				{
					cur = cur->_right;
				}
				else
				{
					cur = cur->_left;
				}
			}

			return nullptr;
		}//Find

		bool Pop(K x)
		{
			Node* cur = _root;
			Node* parent = _root;

			while (cur)
			{
				if ((cur->_val == 3) && (x == 3))
					int b = 10;

				if (cur->_val == x)
				{
					//这个地方我们准备删除了, 因为找到了~ 

					//1.如果cur左为空 -> 让父亲去接管cur的右
					if (cur->_left == nullptr)
					{
						//特殊情况, 假如说删除的就是根呢? 
						if (cur == _root)
						{
							//让根的右成为新的树
							_root = _root->_right;
							delete cur;

							return true;
						}

						//这里需要判断cur是parent的左还是右...
						if (parent->_left == cur)
						{
							parent->_left = cur->_right;
						}
						else
						{
							parent->_right = cur->_right;
						}
						delete cur;
					}//1.如果cur左为空
					//2.如果cur右为空 -> 让父亲去接管cur的左
					else if (cur->_right == nullptr)
					{
						//特殊情况, 假如说删除的就是根呢? 
						if (cur == _root)
						{
							//让根的左成为新的树
							_root = _root->_left;
							delete cur;

							return true;
						}

						//这里需要判断cur是parent的左还是右...
						if (parent->_left == cur)
						{
							parent->_left = cur->_left;
						}
						else
						{
							parent->_right = cur->_left;
						}
						delete cur;
					}//2.如果cur右为空
					//3. 第三种情况, 就是cur左右都有孩子~ 
					else
					{
						//3.1找到右子树中最大的结点
						Node* MinCur = cur->_right;
						Node* MinParent = cur;

						while (MinCur->_left)
						{
							MinParent = MinCur;
							MinCur = MinCur->_left;
						}
						//3.2交换
						swap(MinCur->_val, cur->_val);

						//3.3调整孩子...
						if (MinParent->_left == MinCur)
						{
							MinParent->_left = MinCur->_right;
						}
						else if (MinParent->_right == MinCur)
						{
							MinParent->_right = MinCur->_right;
						}

						//3.4删除
						delete MinCur;
					}//3.cur左右都有孩子~ 

					return true; //表示删除成功~ 
				}
				else if (cur->_val < x)
				{
					parent = cur;
					cur = cur->_right;
				}
				else
				{
					parent = cur;
					cur = cur->_left;
				}
			}

			//如果这个结点压根就不存在, 肯定就不能删除咯~ 包括空树 
			return false;
		}//Pop

		void InOrder()
		{
			_InOrder(_root);
		}

		void _InOrder(Node* node)
		{
			if (node == nullptr)
			{
				cout << "N" << " ";
				return;
			}

			_InOrder(node->_left);
			cout << node->_val << " ";
			_InOrder(node->_right);
		}

	};//BSTree

	void K::kv_test()
	{
		int a[] = { 8, 3, 1, 10, 6, 4, 7, 14, 13 };
		KV::BSTree<int, int> tree;

		for (const auto& e : a)
		{
			tree.Push(e, e);
			tree.InOrder();
			cout << endl;
		}

		for (const auto& e : a)
		{
			KV::BSTreeNode<int, int>* find = tree.Find(e);
			if (find)
			{
				cout << "k: " << find->_val << " and v: " << find->_vue << endl;
			}
		}

		for (const auto& e : a)
		{
			tree.Pop(e);
			tree.InOrder();
			cout << endl;
		}
	}
}

#include"BinarySearchTree.h"

int main()
{
	K::k_test();

	KV::kv_test();
	return 0;
}

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原因分析：

定义在命名空间域中的函数前面多写了个"K::" …

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解决方案：

去掉多写的"K::"即可~

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EOF