c++ delete不能作用于栈上的对象

最新推荐文章于 2025-02-25 23:36:40 发布

原创最新推荐文章于 2025-02-25 23:36:40 发布 · 1.1k 阅读

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本文通过修改测试代码中的对象分配方式，解决了二叉树类在进行深拷贝时遇到的析构函数错误问题。

c++ primer Exercise 13.28，兴冲冲地写出了一个支持深拷贝的二叉树，测试却在destructor那里一直出bug。这是我的树

class TreeNode {
public:
	TreeNode(string val = "", int cnt = 0) :value(val), count(cnt), left(nullptr), right(nullptr) {};
	TreeNode(const TreeNode &node) :value(node.value), count(node.count)	{
		if (node.left)
			left = new TreeNode(*node.left);
		if (node.right)
			right = new TreeNode(*node.right);
	};
	TreeNode &operator=(const TreeNode &node) {
		value = node.value;
		count = node.count;
		if (node.left)
			left = new TreeNode(*node.left);
		if (node.right)
			right = new TreeNode(*node.right);
	}
	TreeNode &add_left(TreeNode *node) {
		left = node;
		return *this;
	}
	TreeNode &add_right(TreeNode *node) {
		right = node;
		return *this;
	}
	~TreeNode() {
		cout << "destructing " <<value<< endl;		
		delete left;
		left = nullptr;	
		delete right;
		right = nullptr;
	}
private:
	string value;
	int count;
	TreeNode *left;
	TreeNode *right;
};

class BinStrTree {
public:
	//BinStrTree() :root(new TreeNode) {};
	BinStrTree(TreeNode *rt) :root(rt) {};
	~BinStrTree() {
		delete root;
	}
private:
	TreeNode * root;
};

这是我的测试代码

TreeNode root("root", 1);
TreeNode left("left", 2);
TreeNode right("right", 3);
root->add_left(&left);
root->add_right(&right);

{
	BinStrTree btree(&root);
}

结果就是析构不了,invalid memory block之类的，查了下，原来delete只能作用于动态分配的内存上，也就是分配在堆上的对象，而不能作用于栈上的对象。如此，把测试对象都改成动态分配的对象就ok了。

TreeNode *root=new TreeNode("root", 1);
TreeNode *left=new TreeNode("left", 2);
TreeNode *right=new TreeNode("right", 3);
root->add_left(left);
root->add_right(right);

{
	BinStrTree btree(root);
}