diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/libstd/primitive_docs.rs | 32 |
1 files changed, 11 insertions, 21 deletions
diff --git a/src/libstd/primitive_docs.rs b/src/libstd/primitive_docs.rs index ad93fe0094a..b840e51873e 100644 --- a/src/libstd/primitive_docs.rs +++ b/src/libstd/primitive_docs.rs @@ -50,18 +50,21 @@ mod prim_bool { } /// [`String`]: string/struct.String.html /// /// As always, remember that a human intuition for 'character' may not map to -/// Unicode's definitions. For example, emoji symbols such as '❤️' are more than -/// one byte; ❤️ in particular is six: +/// Unicode's definitions. For example, emoji symbols such as '❤️' can be more +/// than one Unicode code point; this ❤️ in particular is two: /// /// ``` /// let s = String::from("❤️"); /// -/// // six bytes times one byte for each element -/// assert_eq!(6, s.len() * std::mem::size_of::<u8>()); +/// // we get two chars out of a single ❤️ +/// let mut iter = s.chars(); +/// assert_eq!(Some('\u{2764}'), iter.next()); +/// assert_eq!(Some('\u{fe0f}'), iter.next()); +/// assert_eq!(None, iter.next()); /// ``` /// -/// This also means it won't fit into a `char`, and so trying to create a -/// literal with `let heart = '❤️';` gives an error: +/// This means it won't fit into a `char`. Trying to create a literal with +/// `let heart = '❤️';` gives an error: /// /// ```text /// error: character literal may only contain one codepoint: '❤ @@ -69,8 +72,8 @@ mod prim_bool { } /// ^~ /// ``` /// -/// Another implication of this is that if you want to do per-`char`acter -/// processing, it can end up using a lot more memory: +/// Another implication of the 4-byte fixed size of a `char`, is that +/// per-`char`acter processing can end up using a lot more memory: /// /// ``` /// let s = String::from("love: ❤️"); @@ -79,19 +82,6 @@ mod prim_bool { } /// assert_eq!(12, s.len() * std::mem::size_of::<u8>()); /// assert_eq!(32, v.len() * std::mem::size_of::<char>()); /// ``` -/// -/// Or may give you results you may not expect: -/// -/// ``` -/// let s = String::from("❤️"); -/// -/// let mut iter = s.chars(); -/// -/// // we get two chars out of a single ❤️ -/// assert_eq!(Some('\u{2764}'), iter.next()); -/// assert_eq!(Some('\u{fe0f}'), iter.next()); -/// assert_eq!(None, iter.next()); -/// ``` mod prim_char { } #[doc(primitive = "unit")] |