Merge pull request #7 from leesper/master

[rust-101.git] / src / part08.rs

diff --git a/src/part08.rs b/src/part08.rs
index d6b6782e5fb5d2f42e11d073a3182894acd9b96c..340de24a88e071f2e2ab68fd54ee646b85fd7e04 100644 (file)
--- a/src/part08.rs
+++ b/src/part08.rs
@@ -17,22 +17,22 @@ fn overflowing_add(a: u64, b: u64, carry: bool) -> (u64, bool) {
     //@ The reason for this is that many serious security vulnerabilities have been caused by integer overflows, so just assuming
     //@ "per default" that they are intended is dangerous. <br/>
     //@ If you explicitly *do* want an overflow to happen, you can call the `wrapping_add`
     //@ The reason for this is that many serious security vulnerabilities have been caused by integer overflows, so just assuming
     //@ "per default" that they are intended is dangerous. <br/>
     //@ If you explicitly *do* want an overflow to happen, you can call the `wrapping_add`

-    //@ function (see [the documentation](http://doc.rust-lang.org/stable/std/primitive.u64.html#method.wrapping_add),
+    //@ function (see [the documentation](https://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.
     //@ there are similar functions for other arithmetic operations). There are also similar functions
     //@ `checked_add` etc. to enforce the overflow check.

-    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 {
         // 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.

-        (sum + if carry { 1 } else { 0 }, true)                                 /*@*/
+        (sum + if carry { 1 } else { 0 }, true)                     /*@*/

     }
 }
 
     }
 }
 


@@ -57,7 +57,7 @@ fn test_overflowing_add() {
 impl ops::Add<BigInt> for BigInt {
     //@ Besides static functions and methods, traits can contain *associated types*: This is a type chosen by every particular implementation
     //@ of the trait. The methods of the trait can then refer to that type. In the case of addition, it is used to give the type of the result.
 impl ops::Add<BigInt> for BigInt {
     //@ Besides static functions and methods, traits can contain *associated types*: This is a type chosen by every particular implementation
     //@ of the trait. The methods of the trait can then refer to that type. In the case of addition, it is used to give the type of the result.

-    //@ (Also see the [documentation of `Add`](http://doc.rust-lang.org/stable/std/ops/trait.Add.html).)
+    //@ (Also see the [documentation of `Add`](https://doc.rust-lang.org/stable/std/ops/trait.Add.html).)

     //@ 
     //@ In general, you can consider the two `BigInt` given above (in the `impl` line) *input* types of trait search: When
     //@ `a + b` is invoked with `a` having type `T` and `b` having type `U`, Rust tries to find an implementation of `Add` for
     //@ 
     //@ In general, you can consider the two `BigInt` given above (in the `impl` line) *input* types of trait search: When
     //@ `a + b` is invoked with `a` having type `T` and `b` having type `U`, Rust tries to find an implementation of `Add` for


@@ -91,13 +91,13 @@ impl ops::Add<BigInt> for BigInt {
     }
 }
 
     }
 }
 

-// ## Traits and borrowed types
+// ## Traits and reference types

 //@ If you inspect the addition function above closely, you will notice that it actually consumes ownership of both operands
 //@ to produce the result. This is, of course, in general not what we want. We'd rather like to be able to add two `&BigInt`.
 
 // 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
 //@ If you inspect the addition function above closely, you will notice that it actually consumes ownership of both operands
 //@ to produce the result. This is, of course, in general not what we want. We'd rather like to be able to add two `&BigInt`.
 
 // 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 {
 impl<'a, 'b> ops::Add<&'a BigInt> for &'b BigInt {
     type Output = BigInt;
     fn add(self, rhs: &'a BigInt) -> Self::Output {


@@ -152,4 +152,4 @@ mod tests {
 // **Exercise 08.6**: Write a subtraction function, and testcases for it. Decide for yourself how you want to handle negative results.
 // For example, you may want to return an `Option`, to panic, or to return `0`.
 
 // **Exercise 08.6**: Write a subtraction function, and testcases for it. Decide for yourself how you want to handle negative results.
 // For example, you may want to return an `Option`, to panic, or to return `0`.
 

-//@ [index](main.html) | [previous](part07.html) | [next](part09.html)
+//@ [index](main.html) | [previous](part07.html) | [raw source](https://www.ralfj.de/git/rust-101.git/blob_plain/HEAD:/workspace/src/part08.rs) | [next](part09.html)