gistfile1.c

//We use a typedef to make things simpler
typedef void (*rxt_enumerator)(char *key, char *value);

void rxt_enumerate_node(rxt_node *root, rxt_enumerator callback) {
  if (!root) return;

	if (root->color) {
		if (root->color == 2) root = root->value;
    //All we change is that instead of printing out, we now call the function supplied to us
		if (callback) callback(root->key, root->value);
		return;
	}

	rxt_enumerate_node(root->left, callback);
	rxt_enumerate_node(root->right, callback);
}


//To print as before we create the following function
void printKeyValuePair(char *key, char *value) {
	printf("%s: %s\n", root->key, (char*)root->value);
}

//Then you call rxt_enumerate_node() and pass in the supplied function
void someFunction() {
	rxt_enumerate_node(myNode, printKeyValuePair);
}