How to delete a node of an octree c++ ( node was 0x4.)

问题

I have an Octree and I have to delete a node searched by it's branch. The program can find the node but I'm struggled with delete it. When I create an object of my Octree and I create some nodes but I don't delete them, then the destructor is delete the Octree :

Octree::~Octree()
{
clear(root);
}

void Octree::clear(node *node){
for (int i = 0; i < 8; i++)
    if (node->child[i])
        clear(node->child[i]);

delete node;
}

But when I'd like to delete a concrete node with this method,

void Octree::deletebranch(int branch) {
node *n = search(branch);
if (n) {
    for (int i = 0; i < 8; i++) {
        if (n->child[i]) {
            delete n->child[i];
            n->child[i] = NULL;
        }
    }
    delete n;
    n = NULL;
}
else {
    printf("There is nothing to delete here");
}
}

I got an exception after the destructor called. Exception thrown: read access violation. node was 0x4.

I was debugging step by step and I found some wierd things. When I create a node I do it this way :

        n = new node;
        n->value = xvalue;
        for (int i = 0; i < 8; i++)
            n->child[i] = NULL;

And it's okay I set the value and the node's value is xvalue and the children are NULL. But after I deleted that node with deletebranch() method my node has changed like this.

n 0x00500788 {value=0 child=0x0050078c {0x00000004 {value=??? child=0x00000008 {???, ???, ???, ???, ???, ...} }, ...} } Octree::node * value 0 int
child 0x0050078c {0x00000004 {value=??? child=0x00000008 {???, ???, ???, ???, ???, ???, ???, ???} }, 0xfdfdfdfd {...}, ...} Octree::node *[8]
[0] 0x00000004 {value=??? child=0x00000008 {???, ???, ???, ???, ???, ???, ???, ???} } Octree::node *
[1] 0xfdfdfdfd {value=??? child=0xfdfdfe01 {???, ???, ???, ???, ???, ???, ???, ???} } Octree::node *
[2] 0xdddddddd {value=??? child=0xdddddde1 {???, ???, ???, ???, ???, ???, ???, ???} } Octree::node *
[3] 0x29122f71 {value=??? child=0x29122f75 {???, ???, ???, ???, ???, ???, ???, ???} } Octree::node *
[4] 0x0000a9bd {value=??? child=0x0000a9c1 {???, ???, ???, ???, ???, ???, ???, ???} } Octree::node *
[5] 0x004d5228 {value=5249384 child=0x004d522c {0x005007a0 {value=5067304 child=0x005007a4 {0x004fe218 {...}, ...} }, ...} } Octree::node *
[6] 0x004fe218 {value=5244832 child=0x004fe21c {0x004d00c4 {value=5235224 child=0x004d00c8 {0x00501968 {...}, ...} }, ...} } Octree::node *
[7] 0xdddddddd {value=??? child=0xdddddde1 {???, ???, ???, ???, ???, ???, ???, ???} } Octree::node *
this 0x0043f818 {root=0x005006b0 {value=0 child=0x005006b4 {0x00000000 , 0x00000000 , 0x00000000 , ...} } } Octree *

I really don't understand why is that because I have never changed the node after I deleted it. And I think that's why I got that exception in the destructor. How should I delete a node? Maybe try catch?

Here is the header file:

class Octree
{ 
public:
struct node
{
    int value;
    node *child[8];
};

Octree();
~Octree();

void clear(node* node);
int convert(int sorszam);
node* searchandset(int dec, int value);
node *search(int dec);
node* step(node *node, int k);
void Print(node *n)const;
void put(int branch, int value);
void deletebranch(int branch);
node *root;
};

来源：https://stackoverflow.com/questions/37252439/how-to-delete-a-node-of-an-octree-c-node-was-0x4

标签

c++

octree