Total in FP and OOP

01-multiples.rs

/***
*
* If we list all the natural numbers below 10 that are multiples of 3 or 5, we
* get 3, 5, 6 and 9. The sum of these multiples is 23.
*
* Find the sum of all the multiples of 3 or 5 below 1000.
*
***/

fn is_multiple(num: int) -> bool {
    num % 3 == 0 || num % 5 == 0
}

fn total_oop(max: int) -> int {
    //! Returns the total in an OOP manner
    let mut total = 0;
    for n in range(0, max) {
        if is_multiple(n) {
            total += n
        }
    };
    total
}

fn total_functional(max: int) -> int {
    //! Returns the total in without mutable state
    range(0, max).filter(|&n| is_multiple(n)).fold(0, |a, b| a + b)
}

fn main() -> () {
    println!("Total is {:d}", total_oop(1000))
}

#[test]
fn test_seven_is_not_multiple() {
    if is_multiple(7) {
        fail!("7 is not a multiple of 3 or 5");
    }
}

#[test]
fn test_five_is_multiple() {
    if !is_multiple(5) {
        fail!("Five is multiple of 5!")
    }
}

#[test]
fn test_nine_is_multiple() {
    if !is_multiple(9) {
        fail!("Five is multiple of 9!")
    }
}