C implementation of a binary tree

tree.c

#include <stdio.h>
#include <stdlib.h>

struct tree
{
    struct tree *left;
    int value;
    struct tree *right;
};

typedef struct tree * treep;

treep new(int value) {
  treep t = malloc(sizeof(struct tree));
  t->value = value;
  t->left  = NULL;
  t->right = NULL;

  return t;
}

void insert(treep* tp, int value) {
  treep t = *tp; 
  if (t == NULL)
    *tp = new(value);
  else if (value < t->value) 
    insert(&(t->left), value);
  else if (value > t->value)
    insert(&(t->right), value);
}

void traverse(treep t){
  if (t != NULL) {
    traverse(t->left);
    printf("%d\n", t->value);
    traverse(t->right);
  }
}

int main()
{
  treep t = NULL;
  insert(&t, 4);
  insert(&t, 2);
  insert(&t, 6);
  insert(&t, 1);
  insert(&t, 3);
  insert(&t, 5);
  insert(&t, 7);
  traverse(t);
  return 0;
}