tiny_tree.rs -- A Rust port of my original tiny_tree.c: https://gist.github.com/lelandbatey/99f3c4b99c621c12631d

tiny_tree_print.rs

use std::os;
use std::num::Int;

// Helper function to print out single characters repeatedly.
fn repeat_char(ch: char, mut n: i32){
	while n > 0 {
		print!("{}", ch.to_string());
		n = n-1;
	}
}

fn main() {
	let args = os::args();

	// The user can specify a command line argument for the `height`, and
	// without an argument `height` defaults to a value of `5`
	let mut height = 
		if args.len() > 1 {
			let temp : i32 = match args[1].parse() {
				Some(value) => value,
				None        => panic!("Argument given needs to be integer.")
			};
			temp
		} else {
			5i32
		};

	// Instead of using bit shifting for powers of two, we use the power
	// system, since it's clearer what's going on
	height = 2.pow(height as usize);
	let mut base = height;

	while base > 0 {
		base /= 2;

		// Determine number of "nodes" to print on a line
		let mut i =
			if base > 0 {
				height / base
			} else {
				0i32
			};

		// Print the nodes on a line.
		while i > 0 {
			repeat_char(' ', base-1);
			let mod_i = i%2;
			let mystery_char = 
				if mod_i == 0 {
					'@'
				} else {
					' '
				};
			repeat_char(mystery_char, 1);
			i = i-1;
		}
		print!("\n");
	}
}