Sum of N, Rust version

sum_of_n.rs

#[no_mangle]
pub fn sum_of_n_unsigned(n: usize) -> usize {
    let mut total = 0;
    for i in 1..=n {
        total += i;
    }
    total
}

#[no_mangle]
pub fn sum_of_n_signed(n: i32) -> i32 {
    let mut total = 0;
    for i in 1..=n {
        total += i;
    }
    total
}