paint_calculator.rs

use std::io;
use std::io::Write;
use std::str::FromStr;

fn prompt<F>(question: &str) -> Result<F, F::Err>
    where F: FromStr
{
    let mut answer = String::new();
    print!("{} ", question);
    let _ = io::stdout().flush();
    let _ = io::stdin().read_line(&mut answer);
    answer.trim().to_string().parse::<F>()
}

fn main() {
    let width: u32 = prompt("Width in feet").unwrap();
    let length: u32 = prompt("Length in feet").unwrap();
    let area = width * length;
    let square_feet_per_gallon = 350;
    let gallons;

    if 0 == area % square_feet_per_gallon {
        gallons = area / square_feet_per_gallon;
    } else {
        gallons = (area / square_feet_per_gallon) + 1;
    }

    println!("You will need to purchase {} gallons to cover {} square feet",
             gallons,
             area);

}