Merge pull request #21214 from sleepynate/spacing-in-book

[rust.git] / src / doc / trpl / ownership.md

diff --git a/src/doc/trpl/ownership.md b/src/doc/trpl/ownership.md
index cec85f9facf8fdce6f0cd5de6ba17311bfcf7efb..7a397ce535470bf1ff2039fe896648368ff10e50 100644 (file)
--- a/src/doc/trpl/ownership.md
+++ b/src/doc/trpl/ownership.md
@@ -81,7 +81,6 @@ therefore deallocates the memory for you. Here's the equivalent example in
 Rust:
 
 ```rust
-# use std::boxed::Box;
 {
     let x = Box::new(5);
 }
@@ -101,7 +100,6 @@ This is pretty straightforward, but what happens when we want to pass our box
 to a function? Let's look at some code:
 
 ```rust
-# use std::boxed::Box;
 fn main() {
     let x = Box::new(5);
 
@@ -117,7 +115,6 @@ This code works, but it's not ideal. For example, let's add one more line of
 code, where we print out the value of `x`:
 
 ```{rust,ignore}
-# use std::boxed::Box;
 fn main() {
     let x = Box::new(5);
 
@@ -151,7 +148,6 @@ To fix this, we can have `add_one` give ownership back when it's done with the
 box:
 
 ```rust
-# use std::boxed::Box;
 fn main() {
     let x = Box::new(5);
 
@@ -207,6 +203,26 @@ fn add_one(num: &mut i32) {
 This function borrows an `i32` from its caller, and then increments it. When
 the function is over, and `num` goes out of scope, the borrow is over.
 
+We have to change our `main` a bit too:
+
+```rust
+fn main() {
+    let mut x = 5;
+
+    add_one(&mut x);
+
+    println!("{}", x);
+}
+
+fn add_one(num: &mut i32) {
+    *num += 1;
+}
+```
+
+We don't need to assign the result of `add_one()` anymore, because it doesn't
+return anything anymore. This is because we're not passing ownership back,
+since we just borrow, not take ownership.
+
 # Lifetimes
 
 Lending out a reference to a resource that someone else owns can be
@@ -310,7 +326,7 @@ valid for. For example:
 
 ```rust
 fn main() {
-    let y = &5;    // -+ y goes into scope
+    let y = &5;     // -+ y goes into scope
                     //  |
     // stuff        //  |
                     //  |
@@ -325,7 +341,7 @@ struct Foo<'a> {
 }
 
 fn main() {
-    let y = &5;          // -+ y goes into scope
+    let y = &5;           // -+ y goes into scope
     let f = Foo { x: y }; // -+ f goes into scope
     // stuff              //  |
                           //  |
@@ -344,7 +360,7 @@ fn main() {
     let x;                    // -+ x goes into scope
                               //  |
     {                         //  |
-        let y = &5;          // ---+ y goes into scope
+        let y = &5;           // ---+ y goes into scope
         let f = Foo { x: y }; // ---+ f goes into scope
         x = &f.x;             //  | | error here
     }                         // ---+ f and y go out of scope