Binary trees

#include<iostream>
using namespace std;
template<typename T>
struct node
{
    node(T data) { field = data; }
    T field;
    node *left = nullptr;
    node *right = nullptr;
};


void output_in(node<int> *q) //in-order
{
    if (q == nullptr) return;
    output_in(q->left);
    cout << q->field << " ";
    output_in(q->right);
}

void output_pre(node<int> *q) //pre-order
{
    if (q == nullptr) return;
    cout << q->field << " ";
    output_pre(q->left);
    output_pre(q->right);
}

void output_post(node<int> *q) //post-order
{
    if (q == nullptr) return;
    output_post(q->left);
    output_post(q->right);
    cout << q->field << " ";
}

void destroy_tree(node<int> *q)
{
    if (q == nullptr) return;
    destroy_tree(q->left);
    destroy_tree(q->right);
    delete q;
}

int main()
{
    node<int> *root = new node<int>(1);
    root->left = new node<int>(2);
    root->left->left = new node<int>(4);
    root->left->right = new node<int>(5);
    root->right = new node<int>(3);

    cout << "In-order:\t";     output_in(root);    cout << endl;
    cout << "Pre-order:\t";   output_pre(root);   cout << endl;
    cout << "Post-order:\t";  output_post(root);  cout << endl;

    destroy_tree(root);
    return 0;
}