// So, let us write a function to "add with carry", and give it the appropriate type. Notice Rust's native support for pairs.
fn overflowing_add(a: u64, b: u64, carry: bool) -> (u64, bool) {
- let sum = u64::wrapping_add(a, b);
+ let sum = a.wrapping_add(b);
// If an overflow happened, then the sum will be smaller than *both* summands. Without an overflow, of course, it will be
// at least as large as both of them. So, let's just pick one and check.
if sum >= a {
// **Exercise 08.1**: Write the code to handle adding the carry in this case.
unimplemented!()
} else {
- // The addition *did* overflow. It is impossible for the addition of the carry
+ // Otherwise, the addition *did* overflow. It is impossible for the addition of the carry
// to overflow again, as we are just adding 0 or 1.
unimplemented!()
}
}
}
-// ## Traits and borrowed types
+// ## Traits and reference types
// Writing this out becomes a bit tedious, because trait implementations (unlike functions) require full explicit annotation
// of lifetimes. Make sure you understand exactly what the following definition says. Notice that we can implement a trait for
-// a borrowed type!
+// a reference type!
impl<'a, 'b> ops::Add<&'a BigInt> for &'b BigInt {
type Output = BigInt;
fn add(self, rhs: &'a BigInt) -> Self::Output {
// Rust calls a bunch of definitions that are grouped together a *module*. You can put the tests in a submodule as follows.
#[cfg(test)]
mod tests {
- #[test]
+ use part05::BigInt;
+
+ /*#[test]*/
fn test_add() {
let b1 = BigInt::new(1 << 32);
let b2 = BigInt::from_vec(vec![0, 1]);