Binary tree

void preorder(node *n) {
    cout << n->value;
    if(n->left!=NULL)
        preorder(n->left);
    if (n->right != NULL)
        preorder(n->right);
}
void inorder(node *n) {
    if (n->left != NULL)
        inorder(n->left);
    cout << n->value;
    if (n->right != NULL)
        inorder(n->right);
}
void postorder(node *n) {
    if (n->left != NULL)
        postorder(n->left);
    if (n->right != NULL)
        postorder(n->right);
    cout << n->value;
}