c++ - double free or corruption (out) when trying to delete Nodes in a Binary tree -

i'm trying make recursive function delete nodes in binary tree, p->left , p->right pointers next level in tree. gives following error message:

* error in `./test.out': double free or corruption (out): 0x00007ffdf0cb3650 *

struct node {     int key;     double data;     node * right;     node * left; };  void delete_tree(node * & p){   if (p->left){     delete_tree(p->left);   }   if (p->right){     delete_tree(p->right);   }   delete p; };  int main(){   node * currentnod = new node;   currentnod->key = 5;   node * newnode = new node;   newnode->key = 3;   node * newnode2 = new node;   newnode2->key = 6;   delete_tree(currentnod);   std::cout << currentnod->key << "\n";   std::cout << newnode->key << "\n";   std::cout << currentnod->left->key << "\n";   return 0; 

i've searched online , realize there can problems when have recursive functions pointers, delete_tree takes reference, not copy, problem should not apply here? don't understand why it's not working :(

edit: changed code, problem when initializing currentnod first created node object, , let currentnod pointer object. when instead initialize this, works. however, not print expect. prints:

0 3 segmentation fault

when expect give segmentation fault right away. have idea problem now? :)

it make lot more sense recast destructor:

class node { public:     // constructor, methods, ...     // destructor     ~node(); private:     int key;     double data;     node * right;     node * left; };  node::~node(){     delete left;     delete right;     left = right = nullptr; // see note below }; 

then need delete node; wherever want delete tree. if it's subtree need ensure parent's pointer node nulled don't double-delete.