[英]Access Violation Exception in Visual Studio in Deletion of node in Binary Search Tree
I am getting Exception when running the BST Deletion
. 运行
BST Deletion
时出现异常。 Below is my code snippet: 以下是我的代码段:
Bst::node * Bst::del(node *root, int num)
{
if (root == NULL)
{
return root;
}
else if (num < root->data)
{
root->left = del(root->left, num);
}
else if (num > root->data)
{
root->right = del(root->right, num);
}
else
{
if (root->left == NULL)
{
node * tmp = root;
root = root->right;
delete tmp;
}
else if (root->right == NULL)
{
node * tmp = root;
root = root->left;
delete tmp;
}
else if (root->left == NULL && root->right == NULL)
{
delete root;
root = NULL;
}
else
{
node *tmp = root;
tmp = findMin(root->right);
root->data = tmp->data;
root->right = del(root->right, tmp->data);
}
}
return root;
}
//////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////// //////////////////////
void Bst::del(int num)
{
del(root, num);
}
Everything works fine when I am deleting the other nodes but when I delete the root node itself then the function void Bst::del(int num)
gets the garbage value from the function Bst::node * Bst::del(node *root, int num)
. 当我删除其他节点时,一切正常,但是当我删除根节点本身时,函数
void Bst::del(int num)
从函数Bst::node * Bst::del(node *root, int num)
。 The error gets resolved when I rewrite my function as 当我将函数重写为时,错误得到解决
void Bst::del(int num)
{
root = del(root, num);
}
Question 1. Why it works when I delete the middle nodes or any other node except the root node. 问题1.为什么当我删除中间节点或除根节点之外的任何其他节点时,它可以工作。 While debugging I found that even root was getting deleted properly when the function
Bst::node * Bst::del(node *root, int num)
was executing but when the call returned to the void Bst::del(int num)
then the value of root was not getting retained and was garbage. 在调试时,我发现当执行函数
Bst::node * Bst::del(node *root, int num)
时,即使root也被正确删除Bst::node * Bst::del(node *root, int num)
但是当调用返回到void Bst::del(int num)
根的价值没有得到保留,是垃圾。
Question 2: Why the error got fixed when I stored the returned value in variable root? 问题2:为什么将返回值存储在变量root中时,错误会得到解决?
Assuming you have a member variable named root
, then the problem probably is because you shadow the member variable root
with the argument root
in your deletion function. 假设您有一个名为
root
的成员变量,那么问题可能是因为您在删除函数中用参数root
屏蔽了成员变量root
。 So when you do root = NULL
in the function, you only set the argument to NULL
and not the member variable. 因此,当您在函数中执行
root = NULL
时,仅将参数设置为NULL
而不将成员变量设置为。
There is also the problem with the other assignments to root
, which will just assign to the local argument and not the member variable as well. root
的其他分配也存在问题,它们只会分配给局部参数,而不是成员变量。
The fix you've made (assigning to root
in the calling function) is, I think, the most correct solution. 我认为,您所做的修复(在调用函数中分配为
root
)是最正确的解决方案。
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