Shitty program

Hi /prog/. I'm learning C, and wrote a program that takes a bunch of numbers and sorts them using a binary tree. I know it's not an efficient way to sort, I'm just learning binary trees. Could you look over it real quick and just give me some comments, like if there was something you would have done differently or something that's just stupid. Thanks a lot.

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

struct node_ {
        int value;
        struct node_ *left, *right;
};

typedef struct node_ node;

node *insert(node *parent, int newval)
{
        if (!parent) {
                node *n = malloc(sizeof(node));
                n->value = newval;
                return n;
        }
        else if (newval == parent->value)
                return parent;
        else if (newval < parent->value) {
                parent->left = insert(parent->left, newval);
                return parent;
        }
        else {
                parent->right = insert(parent->right, newval);
                return parent;
        }
}

void print(node *top)
{
        if (!top)
                return;

        print(top->left);
        printf("%d ", top->value);
        print(top->right);
}

int main(int argc, char *argv[])
{
        puts("enter values, 0 to stop");
       
        int next;
        scanf("%d", &next);
       
        node *root = 0;
       
        while (next) {
                root = insert(root, next);
                scanf("%d", &next);
        }

        print(root);
        puts("");

        return 0;
}

>>29
An opaque API can be done with struct node; in the header. I find typedefs like this to be less clear than just using the normal type name. I also find using expressions for sizeof (when possible) nicer than embedding the type name. When you use an expression, allocations usually look like p = malloc(n * sizeof *p);. No type name needed. There's no right answer for either of these issues though, both are a matter of style. Just thought I'd give some food for thought.

scanf is OK for example code, but it actually causes undefined behaviour if the input item for the %d specifier is out of int range (eg sscanf("9999999999999999", "%d", &n);). A combination of fgets and the strto* functions works well.