字符串
现在我们就可以理解 Rust 中的两种字符串类型:
&str
is a slice of UTF-8 encoded bytes, similar to&[u8]
.String
is an owned, heap-allocated buffer of UTF-8 bytes.
Speaker Notes
This slide should take about 10 minutes.
-
&str
introduces a string slice, which is an immutable reference to UTF-8 encoded string data stored in a block of memory. String literals ("Hello"
), are stored in the program’s binary. -
Rust’s
String
type is a wrapper around a vector of bytes. As with aVec<T>
, it is owned. -
As with many other types
String::from()
creates a string from a string literal;String::new()
creates a new empty string, to which string data can be added using thepush()
andpush_str()
methods. -
The
format!()
macro is a convenient way to generate an owned string from dynamic values. It accepts the same format specification asprintln!()
. -
You can borrow
&str
slices fromString
via&
and optionally range selection. If you select a byte range that is not aligned to character boundaries, the expression will panic. Thechars
iterator iterates over characters and is preferred over trying to get character boundaries right. -
For C++ programmers: think of
&str
asstd::string_view
from C++, but the one that always points to a valid string in memory. RustString
is a rough equivalent ofstd::string
from C++ (main difference: it can only contain UTF-8 encoded bytes and will never use a small-string optimization). -
Byte strings literals allow you to create a
&[u8]
value directly: -
原始字符串可在创建
&str
时禁用转义:r"\n" == "\\n"
。可以在外层引号两侧添加相同数量的#
,以在字符串中嵌入双引号: