Create Copy of a tree (cpp)

Given a binary tree,create the copy of the tree. node *copy(node* root)

node *copy(node *root)

 node *temp;
 
 if(root==NULL)return(NULL);
  
 temp = (node *) malloc(sizeof(node));//or temp = newNode(root->data);
 temp->value = root->value;

 temp->left  = copy(root->left);
 temp->right = copy(root->right);

 return(temp);