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Rollup merge of #32478 - xevix:docs/strings-str-unsized-types, r=steveklabnik 

Add note on `str` being an unsized type in strings section of book

The book section on Rust strings mentions `&str` and `String` but does not address why `str` is not used directly. This adds a short blurb and a link to the unsized types chapter. The second draft of the book will go more in-depth on this, but this should help a bit for now. Thanks #rust for clarifying this point, and let me know if it needs rewording or different placement 😄.

CC @steveklabnik @Kimundi
This commit is contained in:
Manish Goregaokar 2016-03-26 20:35:49 +05:30
parent dcfcbaa009 6ce63fb3f1
commit 2c4d039b76
1 changed files with 6 additions and 0 deletions
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6
src/doc/book/strings.md
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@ -44,6 +44,11 @@ let s = "foo\
assert_eq!("foobar", s);
```
Note that you normally cannot access a `str` directly, but only through a `&str`
reference. This is because `str` is an unsized type which requires additional
runtime information to be usable. For more information see the chapter on
[unsized types][ut].
Rust has more than only `&str`s though. A `String` is a heap-allocated string.
This string is growable, and is also guaranteed to be UTF-8. `String`s are
commonly created by converting from a string slice using the `to_string`
@ -185,5 +190,6 @@ let hello_world = hello + &world;
This is because `&String` can automatically coerce to a `&str`. This is a
feature called ‘[`Deref` coercions][dc]’.
[ut]: unsized-types.html
[dc]: deref-coercions.html
[connect]: ../std/net/struct.TcpStream.html#method.connect