//@ function (see [the documentation](http://doc.rust-lang.org/stable/std/primitive.u64.html#method.wrapping_add),
//@ there are similar functions for other arithmetic operations). There are also similar functions
//@ `checked_add` etc. to enforce the overflow check.
//@ function (see [the documentation](http://doc.rust-lang.org/stable/std/primitive.u64.html#method.wrapping_add),
//@ there are similar functions for other arithmetic operations). There are also similar functions
//@ `checked_add` etc. to enforce the overflow check.
// 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 {
// The addition did not overflow. <br/>
// **Exercise 08.1**: Write the code to handle adding the carry in this case.
// 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 {
// The addition did not overflow. <br/>
// **Exercise 08.1**: Write the code to handle adding the carry in this case.
- let sum_total = u64::wrapping_add(sum, if carry { 1 } else { 0 }); /*@@*/
- let had_overflow = sum_total < sum; /*@@*/
- (sum_total, had_overflow) /*@@*/
+ let sum_total = sum.wrapping_add(if carry { 1 } else { 0 });/*@@*/
+ let had_overflow = sum_total < sum; /*@@*/
+ (sum_total, had_overflow) /*@@*/
} else {
// 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.
} else {
// 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.
fn test_add() {
let b1 = BigInt::new(1 << 32);
let b2 = BigInt::from_vec(vec![0, 1]);
fn test_add() {
let b1 = BigInt::new(1 << 32);
let b2 = BigInt::from_vec(vec![0, 1]);