Comment by ramon156

Why not look at how other languages attack this? e.g. how does "42".parse() work in rust?

Edit: https://doc.rust-lang.org/src/core/num/mod.rs.html#1537

interesting! It boils down to this

pub const fn from_ascii_radix(src: &[u8], radix: u32) -> Result<u32, ParseIntError> {

    use self::IntErrorKind::*;

    use self::ParseIntError as PIE;

    // guard: radix must be 2..=36

    if 2 > radix || radix > 36 {

        from_ascii_radix_panic(radix);

    }

    if src.is_empty() {

        return Err(PIE { kind: Empty });

    }

    // Strip leading '+' or '-', detect sign

    // (a bare '+' or '-' with nothing after it is an error)

    // accumulate digits, checking for overflow

    Ok(result)

}