Question

How to get the Nth digit of a number in Rust

Answer 1

/// Returns the N-th digit of a number counting from the left.
///
/// Examples:
/// - get_nth_digit_from_left(12345, 1) -> 1
/// - get_nth_digit_from_left(12745, 3) -> 7
fn get_nth_digit_from_left(input_number: i64, digit_position: usize) -> Result<u8, String> {
    let digit_string = input_number.abs().to_string();

    if digit_position == 0 || digit_position > digit_string.len() {
        return Err("Digit position is out of range.".to_string());
    }

    let digit = digit_string
        .chars()
        .nth(digit_position - 1)
        .unwrap()
        .to_digit(10)
        .unwrap() as u8;

    Ok(digit)
}

fn main() {
    let account_number = 987654321;

    let fourth_digit_from_left =
        get_nth_digit_from_left(account_number, 4).unwrap();

    println!("Fourth digit from left: {}", fourth_digit_from_left);
}


/*
run:

Fourth digit from left: 6

*/

 

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