Primitive Type str
1.0.0 ·Expand description
String slices.
The str
type, also called a ‘string slice’, is the most primitive string
type. It is usually seen in its borrowed form, &str
. It is also the type
of string literals, &'static str
.
§Basic Usage
String literals are string slices:
let hello_world = "Hello, World!";
RunHere we have declared a string slice initialized with a string literal.
String literals have a static lifetime, which means the string hello_world
is guaranteed to be valid for the duration of the entire program.
We can explicitly specify hello_world
’s lifetime as well:
let hello_world: &'static str = "Hello, world!";
Run§Representation
A &str
is made up of two components: a pointer to some bytes, and a
length. You can look at these with the as_ptr
and len
methods:
use std::slice;
use std::str;
let story = "Once upon a time...";
let ptr = story.as_ptr();
let len = story.len();
// story has nineteen bytes
assert_eq!(19, len);
// We can re-build a str out of ptr and len. This is all unsafe because
// we are responsible for making sure the two components are valid:
let s = unsafe {
// First, we build a &[u8]...
let slice = slice::from_raw_parts(ptr, len);
// ... and then convert that slice into a string slice
str::from_utf8(slice)
};
assert_eq!(s, Ok(story));
RunNote: This example shows the internals of &str
. unsafe
should not be
used to get a string slice under normal circumstances. Use as_str
instead.
§Invariant
Rust libraries may assume that string slices are always valid UTF-8.
Constructing a non-UTF-8 string slice is not immediate undefined behavior, but any function called on a string slice may assume that it is valid UTF-8, which means that a non-UTF-8 string slice can lead to undefined behavior down the road.
Implementations§
source§impl str
impl str
1.9.0 · sourcepub fn is_char_boundary(&self, index: usize) -> bool
pub fn is_char_boundary(&self, index: usize) -> bool
Checks that index
-th byte is the first byte in a UTF-8 code point
sequence or the end of the string.
The start and end of the string (when index == self.len()
) are
considered to be boundaries.
Returns false
if index
is greater than self.len()
.
§Examples
let s = "Löwe 老虎 Léopard";
assert!(s.is_char_boundary(0));
// start of `老`
assert!(s.is_char_boundary(6));
assert!(s.is_char_boundary(s.len()));
// second byte of `ö`
assert!(!s.is_char_boundary(2));
// third byte of `老`
assert!(!s.is_char_boundary(8));
Runsourcepub fn floor_char_boundary(&self, index: usize) -> usize
🔬This is a nightly-only experimental API. (round_char_boundary
#93743)
pub fn floor_char_boundary(&self, index: usize) -> usize
round_char_boundary
#93743)Finds the closest x
not exceeding index
where is_char_boundary(x)
is true
.
This method can help you truncate a string so that it’s still valid UTF-8, but doesn’t exceed a given number of bytes. Note that this is done purely at the character level and can still visually split graphemes, even though the underlying characters aren’t split. For example, the emoji 🧑🔬 (scientist) could be split so that the string only includes 🧑 (person) instead.
§Examples
#![feature(round_char_boundary)]
let s = "❤️🧡💛💚💙💜";
assert_eq!(s.len(), 26);
assert!(!s.is_char_boundary(13));
let closest = s.floor_char_boundary(13);
assert_eq!(closest, 10);
assert_eq!(&s[..closest], "❤️🧡");
Runsourcepub fn ceil_char_boundary(&self, index: usize) -> usize
🔬This is a nightly-only experimental API. (round_char_boundary
#93743)
pub fn ceil_char_boundary(&self, index: usize) -> usize
round_char_boundary
#93743)Finds the closest x
not below index
where is_char_boundary(x)
is true
.
If index
is greater than the length of the string, this returns the length of the string.
This method is the natural complement to floor_char_boundary
. See that method
for more details.
§Examples
#![feature(round_char_boundary)]
let s = "❤️🧡💛💚💙💜";
assert_eq!(s.len(), 26);
assert!(!s.is_char_boundary(13));
let closest = s.ceil_char_boundary(13);
assert_eq!(closest, 14);
assert_eq!(&s[..closest], "❤️🧡💛");
Run1.20.0 · sourcepub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] ⓘ
pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] ⓘ
Converts a mutable string slice to a mutable byte slice.
§Safety
The caller must ensure that the content of the slice is valid UTF-8
before the borrow ends and the underlying str
is used.
Use of a str
whose contents are not valid UTF-8 is undefined behavior.
§Examples
Basic usage:
let mut s = String::from("Hello");
let bytes = unsafe { s.as_bytes_mut() };
assert_eq!(b"Hello", bytes);
RunMutability:
let mut s = String::from("🗻∈🌏");
unsafe {
let bytes = s.as_bytes_mut();
bytes[0] = 0xF0;
bytes[1] = 0x9F;
bytes[2] = 0x8D;
bytes[3] = 0x94;
}
assert_eq!("🍔∈🌏", s);
Run1.0.0 (const: 1.32.0) · sourcepub const fn as_ptr(&self) -> *const u8
pub const fn as_ptr(&self) -> *const u8
Converts a string slice to a raw pointer.
As string slices are a slice of bytes, the raw pointer points to a
u8
. This pointer will be pointing to the first byte of the string
slice.
The caller must ensure that the returned pointer is never written to.
If you need to mutate the contents of the string slice, use as_mut_ptr
.
§Examples
let s = "Hello";
let ptr = s.as_ptr();
Run1.36.0 · sourcepub fn as_mut_ptr(&mut self) -> *mut u8
pub fn as_mut_ptr(&mut self) -> *mut u8
Converts a mutable string slice to a raw pointer.
As string slices are a slice of bytes, the raw pointer points to a
u8
. This pointer will be pointing to the first byte of the string
slice.
It is your responsibility to make sure that the string slice only gets modified in a way that it remains valid UTF-8.
1.20.0 · sourcepub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
pub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
Returns a subslice of str
.
This is the non-panicking alternative to indexing the str
. Returns
None
whenever equivalent indexing operation would panic.
§Examples
let v = String::from("🗻∈🌏");
assert_eq!(Some("🗻"), v.get(0..4));
// indices not on UTF-8 sequence boundaries
assert!(v.get(1..).is_none());
assert!(v.get(..8).is_none());
// out of bounds
assert!(v.get(..42).is_none());
Run1.20.0 · sourcepub fn get_mut<I>(
&mut self,
i: I,
) -> Option<&mut <I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
pub fn get_mut<I>(
&mut self,
i: I,
) -> Option<&mut <I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
Returns a mutable subslice of str
.
This is the non-panicking alternative to indexing the str
. Returns
None
whenever equivalent indexing operation would panic.
§Examples
let mut v = String::from("hello");
// correct length
assert!(v.get_mut(0..5).is_some());
// out of bounds
assert!(v.get_mut(..42).is_none());
assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));
assert_eq!("hello", v);
{
let s = v.get_mut(0..2);
let s = s.map(|s| {
s.make_ascii_uppercase();
&*s
});
assert_eq!(Some("HE"), s);
}
assert_eq!("HEllo", v);
Run1.20.0 · sourcepub unsafe fn get_unchecked<I>(&self, i: I) -> &<I as SliceIndex<str>>::Outputwhere
I: SliceIndex<str>,
pub unsafe fn get_unchecked<I>(&self, i: I) -> &<I as SliceIndex<str>>::Outputwhere
I: SliceIndex<str>,
Returns an unchecked subslice of str
.
This is the unchecked alternative to indexing the str
.
§Safety
Callers of this function are responsible that these preconditions are satisfied:
- The starting index must not exceed the ending index;
- Indexes must be within bounds of the original slice;
- Indexes must lie on UTF-8 sequence boundaries.
Failing that, the returned string slice may reference invalid memory or
violate the invariants communicated by the str
type.
§Examples
let v = "🗻∈🌏";
unsafe {
assert_eq!("🗻", v.get_unchecked(0..4));
assert_eq!("∈", v.get_unchecked(4..7));
assert_eq!("🌏", v.get_unchecked(7..11));
}
Run1.20.0 · sourcepub unsafe fn get_unchecked_mut<I>(
&mut self,
i: I,
) -> &mut <I as SliceIndex<str>>::Outputwhere
I: SliceIndex<str>,
pub unsafe fn get_unchecked_mut<I>(
&mut self,
i: I,
) -> &mut <I as SliceIndex<str>>::Outputwhere
I: SliceIndex<str>,
Returns a mutable, unchecked subslice of str
.
This is the unchecked alternative to indexing the str
.
§Safety
Callers of this function are responsible that these preconditions are satisfied:
- The starting index must not exceed the ending index;
- Indexes must be within bounds of the original slice;
- Indexes must lie on UTF-8 sequence boundaries.
Failing that, the returned string slice may reference invalid memory or
violate the invariants communicated by the str
type.
§Examples
let mut v = String::from("🗻∈🌏");
unsafe {
assert_eq!("🗻", v.get_unchecked_mut(0..4));
assert_eq!("∈", v.get_unchecked_mut(4..7));
assert_eq!("🌏", v.get_unchecked_mut(7..11));
}
Run1.0.0 · sourcepub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str
👎Deprecated since 1.29.0: use get_unchecked(begin..end)
instead
pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str
get_unchecked(begin..end)
insteadCreates a string slice from another string slice, bypassing safety checks.
This is generally not recommended, use with caution! For a safe
alternative see str
and Index
.
This new slice goes from begin
to end
, including begin
but
excluding end
.
To get a mutable string slice instead, see the
slice_mut_unchecked
method.
§Safety
Callers of this function are responsible that three preconditions are satisfied:
begin
must not exceedend
.begin
andend
must be byte positions within the string slice.begin
andend
must lie on UTF-8 sequence boundaries.
§Examples
let s = "Löwe 老虎 Léopard";
unsafe {
assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21));
}
let s = "Hello, world!";
unsafe {
assert_eq!("world", s.slice_unchecked(7, 12));
}
Run1.5.0 · sourcepub unsafe fn slice_mut_unchecked(
&mut self,
begin: usize,
end: usize,
) -> &mut str
👎Deprecated since 1.29.0: use get_unchecked_mut(begin..end)
instead
pub unsafe fn slice_mut_unchecked( &mut self, begin: usize, end: usize, ) -> &mut str
get_unchecked_mut(begin..end)
insteadCreates a string slice from another string slice, bypassing safety
checks.
This is generally not recommended, use with caution! For a safe
alternative see str
and IndexMut
.
This new slice goes from begin
to end
, including begin
but
excluding end
.
To get an immutable string slice instead, see the
slice_unchecked
method.
§Safety
Callers of this function are responsible that three preconditions are satisfied:
begin
must not exceedend
.begin
andend
must be byte positions within the string slice.begin
andend
must lie on UTF-8 sequence boundaries.
1.4.0 · sourcepub fn split_at(&self, mid: usize) -> (&str, &str)
pub fn split_at(&self, mid: usize) -> (&str, &str)
Divide one string slice into two at an index.
The argument, mid
, should be a byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get mutable string slices instead, see the split_at_mut
method.
§Panics
Panics if mid
is not on a UTF-8 code point boundary, or if it is past
the end of the last code point of the string slice. For a non-panicking
alternative see split_at_checked
.
§Examples
let s = "Per Martin-Löf";
let (first, last) = s.split_at(3);
assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);
Run1.4.0 · sourcepub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)
pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)
Divide one mutable string slice into two at an index.
The argument, mid
, should be a byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get immutable string slices instead, see the split_at
method.
§Panics
Panics if mid
is not on a UTF-8 code point boundary, or if it is past
the end of the last code point of the string slice. For a non-panicking
alternative see split_at_mut_checked
.
§Examples
let mut s = "Per Martin-Löf".to_string();
{
let (first, last) = s.split_at_mut(3);
first.make_ascii_uppercase();
assert_eq!("PER", first);
assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);
Run1.80.0 · sourcepub fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)>
pub fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)>
Divide one string slice into two at an index.
The argument, mid
, should be a valid byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point. The
method returns None
if that’s not the case.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get mutable string slices instead, see the split_at_mut_checked
method.
§Examples
let s = "Per Martin-Löf";
let (first, last) = s.split_at_checked(3).unwrap();
assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);
assert_eq!(None, s.split_at_checked(13)); // Inside “ö”
assert_eq!(None, s.split_at_checked(16)); // Beyond the string length
Run1.80.0 · sourcepub fn split_at_mut_checked(
&mut self,
mid: usize,
) -> Option<(&mut str, &mut str)>
pub fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut str, &mut str)>
Divide one mutable string slice into two at an index.
The argument, mid
, should be a valid byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point. The
method returns None
if that’s not the case.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get immutable string slices instead, see the split_at_checked
method.
§Examples
let mut s = "Per Martin-Löf".to_string();
if let Some((first, last)) = s.split_at_mut_checked(3) {
first.make_ascii_uppercase();
assert_eq!("PER", first);
assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);
assert_eq!(None, s.split_at_mut_checked(13)); // Inside “ö”
assert_eq!(None, s.split_at_mut_checked(16)); // Beyond the string length
Run1.0.0 · sourcepub fn chars(&self) -> Chars<'_> ⓘ
pub fn chars(&self) -> Chars<'_> ⓘ
Returns an iterator over the char
s of a string slice.
As a string slice consists of valid UTF-8, we can iterate through a
string slice by char
. This method returns such an iterator.
It’s important to remember that char
represents a Unicode Scalar
Value, and might not match your idea of what a ‘character’ is. Iteration
over grapheme clusters may be what you actually want. This functionality
is not provided by Rust’s standard library, check crates.io instead.
§Examples
Basic usage:
let word = "goodbye";
let count = word.chars().count();
assert_eq!(7, count);
let mut chars = word.chars();
assert_eq!(Some('g'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('d'), chars.next());
assert_eq!(Some('b'), chars.next());
assert_eq!(Some('y'), chars.next());
assert_eq!(Some('e'), chars.next());
assert_eq!(None, chars.next());
RunRemember, char
s might not match your intuition about characters:
let y = "y̆";
let mut chars = y.chars();
assert_eq!(Some('y'), chars.next()); // not 'y̆'
assert_eq!(Some('\u{0306}'), chars.next());
assert_eq!(None, chars.next());
Run1.0.0 · sourcepub fn char_indices(&self) -> CharIndices<'_> ⓘ
pub fn char_indices(&self) -> CharIndices<'_> ⓘ
Returns an iterator over the char
s of a string slice, and their
positions.
As a string slice consists of valid UTF-8, we can iterate through a
string slice by char
. This method returns an iterator of both
these char
s, as well as their byte positions.
The iterator yields tuples. The position is first, the char
is
second.
§Examples
Basic usage:
let word = "goodbye";
let count = word.char_indices().count();
assert_eq!(7, count);
let mut char_indices = word.char_indices();
assert_eq!(Some((0, 'g')), char_indices.next());
assert_eq!(Some((1, 'o')), char_indices.next());
assert_eq!(Some((2, 'o')), char_indices.next());
assert_eq!(Some((3, 'd')), char_indices.next());
assert_eq!(Some((4, 'b')), char_indices.next());
assert_eq!(Some((5, 'y')), char_indices.next());
assert_eq!(Some((6, 'e')), char_indices.next());
assert_eq!(None, char_indices.next());
RunRemember, char
s might not match your intuition about characters:
let yes = "y̆es";
let mut char_indices = yes.char_indices();
assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
assert_eq!(Some((1, '\u{0306}')), char_indices.next());
// note the 3 here - the previous character took up two bytes
assert_eq!(Some((3, 'e')), char_indices.next());
assert_eq!(Some((4, 's')), char_indices.next());
assert_eq!(None, char_indices.next());
Run1.0.0 · sourcepub fn bytes(&self) -> Bytes<'_> ⓘ
pub fn bytes(&self) -> Bytes<'_> ⓘ
An iterator over the bytes of a string slice.
As a string slice consists of a sequence of bytes, we can iterate through a string slice by byte. This method returns such an iterator.
§Examples
let mut bytes = "bors".bytes();
assert_eq!(Some(b'b'), bytes.next());
assert_eq!(Some(b'o'), bytes.next());
assert_eq!(Some(b'r'), bytes.next());
assert_eq!(Some(b's'), bytes.next());
assert_eq!(None, bytes.next());
Run1.1.0 · sourcepub fn split_whitespace(&self) -> SplitWhitespace<'_> ⓘ
pub fn split_whitespace(&self) -> SplitWhitespace<'_> ⓘ
Splits a string slice by whitespace.
The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of whitespace.
‘Whitespace’ is defined according to the terms of the Unicode Derived
Core Property White_Space
. If you only want to split on ASCII whitespace
instead, use split_ascii_whitespace
.
§Examples
Basic usage:
let mut iter = "A few words".split_whitespace();
assert_eq!(Some("A"), iter.next());
assert_eq!(Some("few"), iter.next());
assert_eq!(Some("words"), iter.next());
assert_eq!(None, iter.next());
RunAll kinds of whitespace are considered:
let mut iter = " Mary had\ta\u{2009}little \n\t lamb".split_whitespace();
assert_eq!(Some("Mary"), iter.next());
assert_eq!(Some("had"), iter.next());
assert_eq!(Some("a"), iter.next());
assert_eq!(Some("little"), iter.next());
assert_eq!(Some("lamb"), iter.next());
assert_eq!(None, iter.next());
RunIf the string is empty or all whitespace, the iterator yields no string slices:
assert_eq!("".split_whitespace().next(), None);
assert_eq!(" ".split_whitespace().next(), None);
Run1.34.0 · sourcepub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_> ⓘ
pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_> ⓘ
Splits a string slice by ASCII whitespace.
The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of ASCII whitespace.
To split by Unicode Whitespace
instead, use split_whitespace
.
§Examples
Basic usage:
let mut iter = "A few words".split_ascii_whitespace();
assert_eq!(Some("A"), iter.next());
assert_eq!(Some("few"), iter.next());
assert_eq!(Some("words"), iter.next());
assert_eq!(None, iter.next());
RunAll kinds of ASCII whitespace are considered:
let mut iter = " Mary had\ta little \n\t lamb".split_ascii_whitespace();
assert_eq!(Some("Mary"), iter.next());
assert_eq!(Some("had"), iter.next());
assert_eq!(Some("a"), iter.next());
assert_eq!(Some("little"), iter.next());
assert_eq!(Some("lamb"), iter.next());
assert_eq!(None, iter.next());
RunIf the string is empty or all ASCII whitespace, the iterator yields no string slices:
assert_eq!("".split_ascii_whitespace().next(), None);
assert_eq!(" ".split_ascii_whitespace().next(), None);
Run1.0.0 · sourcepub fn lines(&self) -> Lines<'_> ⓘ
pub fn lines(&self) -> Lines<'_> ⓘ
An iterator over the lines of a string, as string slices.
Lines are split at line endings that are either newlines (\n
) or
sequences of a carriage return followed by a line feed (\r\n
).
Line terminators are not included in the lines returned by the iterator.
Note that any carriage return (\r
) not immediately followed by a
line feed (\n
) does not split a line. These carriage returns are
thereby included in the produced lines.
The final line ending is optional. A string that ends with a final line ending will return the same lines as an otherwise identical string without a final line ending.
§Examples
Basic usage:
let text = "foo\r\nbar\n\nbaz\r";
let mut lines = text.lines();
assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
// Trailing carriage return is included in the last line
assert_eq!(Some("baz\r"), lines.next());
assert_eq!(None, lines.next());
RunThe final line does not require any ending:
let text = "foo\nbar\n\r\nbaz";
let mut lines = text.lines();
assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
assert_eq!(Some("baz"), lines.next());
assert_eq!(None, lines.next());
Run1.0.0 · sourcepub fn lines_any(&self) -> LinesAny<'_> ⓘ
👎Deprecated since 1.4.0: use lines() instead now
pub fn lines_any(&self) -> LinesAny<'_> ⓘ
An iterator over the lines of a string.
1.8.0 · sourcepub fn encode_utf16(&self) -> EncodeUtf16<'_> ⓘ
pub fn encode_utf16(&self) -> EncodeUtf16<'_> ⓘ
1.0.0 · sourcepub fn contains<'a, P>(&'a self, pat: P) -> boolwhere
P: Pattern<'a>,
pub fn contains<'a, P>(&'a self, pat: P) -> boolwhere
P: Pattern<'a>,
Returns true
if the given pattern matches a sub-slice of
this string slice.
Returns false
if it does not.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
let bananas = "bananas";
assert!(bananas.contains("nana"));
assert!(!bananas.contains("apples"));
Run1.0.0 · sourcepub fn starts_with<'a, P>(&'a self, pat: P) -> boolwhere
P: Pattern<'a>,
pub fn starts_with<'a, P>(&'a self, pat: P) -> boolwhere
P: Pattern<'a>,
Returns true
if the given pattern matches a prefix of this
string slice.
Returns false
if it does not.
The pattern can be a &str
, in which case this function will return true if
the &str
is a prefix of this string slice.
The pattern can also be a char
, a slice of char
s, or a
function or closure that determines if a character matches.
These will only be checked against the first character of this string slice.
Look at the second example below regarding behavior for slices of char
s.
§Examples
let bananas = "bananas";
assert!(bananas.starts_with("bana"));
assert!(!bananas.starts_with("nana"));
Runlet bananas = "bananas";
// Note that both of these assert successfully.
assert!(bananas.starts_with(&['b', 'a', 'n', 'a']));
assert!(bananas.starts_with(&['a', 'b', 'c', 'd']));
Run1.0.0 · sourcepub fn ends_with<'a, P>(&'a self, pat: P) -> bool
pub fn ends_with<'a, P>(&'a self, pat: P) -> bool
Returns true
if the given pattern matches a suffix of this
string slice.
Returns false
if it does not.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
let bananas = "bananas";
assert!(bananas.ends_with("anas"));
assert!(!bananas.ends_with("nana"));
Run1.0.0 · sourcepub fn find<'a, P>(&'a self, pat: P) -> Option<usize>where
P: Pattern<'a>,
pub fn find<'a, P>(&'a self, pat: P) -> Option<usize>where
P: Pattern<'a>,
Returns the byte index of the first character of this string slice that matches the pattern.
Returns None
if the pattern doesn’t match.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi";
assert_eq!(s.find('L'), Some(0));
assert_eq!(s.find('é'), Some(14));
assert_eq!(s.find("pard"), Some(17));
RunMore complex patterns using point-free style and closures:
let s = "Löwe 老虎 Léopard";
assert_eq!(s.find(char::is_whitespace), Some(5));
assert_eq!(s.find(char::is_lowercase), Some(1));
assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1));
assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));
RunNot finding the pattern:
let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];
assert_eq!(s.find(x), None);
Run1.0.0 · sourcepub fn rfind<'a, P>(&'a self, pat: P) -> Option<usize>
pub fn rfind<'a, P>(&'a self, pat: P) -> Option<usize>
Returns the byte index for the first character of the last match of the pattern in this string slice.
Returns None
if the pattern doesn’t match.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi";
assert_eq!(s.rfind('L'), Some(13));
assert_eq!(s.rfind('é'), Some(14));
assert_eq!(s.rfind("pard"), Some(24));
RunMore complex patterns with closures:
let s = "Löwe 老虎 Léopard";
assert_eq!(s.rfind(char::is_whitespace), Some(12));
assert_eq!(s.rfind(char::is_lowercase), Some(20));
RunNot finding the pattern:
let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];
assert_eq!(s.rfind(x), None);
Run1.0.0 · sourcepub fn split<'a, P>(&'a self, pat: P) -> Split<'a, P> ⓘwhere
P: Pattern<'a>,
pub fn split<'a, P>(&'a self, pat: P) -> Split<'a, P> ⓘwhere
P: Pattern<'a>,
An iterator over substrings of this string slice, separated by characters matched by a pattern.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rsplit
method can be used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);
let v: Vec<&str> = "".split('X').collect();
assert_eq!(v, [""]);
let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
assert_eq!(v, ["lion", "", "tiger", "leopard"]);
let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);
let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect();
assert_eq!(v, ["abc", "def", "ghi"]);
let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);
RunIf the pattern is a slice of chars, split on each occurrence of any of the characters:
let v: Vec<&str> = "2020-11-03 23:59".split(&['-', ' ', ':', '@'][..]).collect();
assert_eq!(v, ["2020", "11", "03", "23", "59"]);
RunA more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect();
assert_eq!(v, ["abc", "def", "ghi"]);
RunIf a string contains multiple contiguous separators, you will end up with empty strings in the output:
let x = "||||a||b|c".to_string();
let d: Vec<_> = x.split('|').collect();
assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
RunContiguous separators are separated by the empty string.
let x = "(///)".to_string();
let d: Vec<_> = x.split('/').collect();
assert_eq!(d, &["(", "", "", ")"]);
RunSeparators at the start or end of a string are neighbored by empty strings.
let d: Vec<_> = "010".split("0").collect();
assert_eq!(d, &["", "1", ""]);
RunWhen the empty string is used as a separator, it separates every character in the string, along with the beginning and end of the string.
let f: Vec<_> = "rust".split("").collect();
assert_eq!(f, &["", "r", "u", "s", "t", ""]);
RunContiguous separators can lead to possibly surprising behavior when whitespace is used as the separator. This code is correct:
let x = " a b c".to_string();
let d: Vec<_> = x.split(' ').collect();
assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
RunIt does not give you:
Use split_whitespace
for this behavior.
1.51.0 · sourcepub fn split_inclusive<'a, P>(&'a self, pat: P) -> SplitInclusive<'a, P> ⓘwhere
P: Pattern<'a>,
pub fn split_inclusive<'a, P>(&'a self, pat: P) -> SplitInclusive<'a, P> ⓘwhere
P: Pattern<'a>,
An iterator over substrings of this string slice, separated by
characters matched by a pattern. Differs from the iterator produced by
split
in that split_inclusive
leaves the matched part as the
terminator of the substring.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
.split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);
RunIf the last element of the string is matched, that element will be considered the terminator of the preceding substring. That substring will be the last item returned by the iterator.
let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n"
.split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);
Run1.0.0 · sourcepub fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P> ⓘ
pub fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P> ⓘ
An iterator over substrings of the given string slice, separated by characters matched by a pattern and yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse
search, and it will be a DoubleEndedIterator
if a forward/reverse
search yields the same elements.
For iterating from the front, the split
method can be used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);
let v: Vec<&str> = "".rsplit('X').collect();
assert_eq!(v, [""]);
let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
assert_eq!(v, ["leopard", "tiger", "", "lion"]);
let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
assert_eq!(v, ["leopard", "tiger", "lion"]);
RunA more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "def", "abc"]);
Run1.0.0 · sourcepub fn split_terminator<'a, P>(&'a self, pat: P) -> SplitTerminator<'a, P> ⓘwhere
P: Pattern<'a>,
pub fn split_terminator<'a, P>(&'a self, pat: P) -> SplitTerminator<'a, P> ⓘwhere
P: Pattern<'a>,
An iterator over substrings of the given string slice, separated by characters matched by a pattern.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
Equivalent to split
, except that the trailing substring
is skipped if empty.
This method can be used for string data that is terminated, rather than separated by a pattern.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rsplit_terminator
method can be used.
§Examples
let v: Vec<&str> = "A.B.".split_terminator('.').collect();
assert_eq!(v, ["A", "B"]);
let v: Vec<&str> = "A..B..".split_terminator(".").collect();
assert_eq!(v, ["A", "", "B", ""]);
let v: Vec<&str> = "A.B:C.D".split_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["A", "B", "C", "D"]);
Run1.0.0 · sourcepub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P> ⓘ
pub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P> ⓘ
An iterator over substrings of self
, separated by characters
matched by a pattern and yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
Equivalent to split
, except that the trailing substring is
skipped if empty.
This method can be used for string data that is terminated, rather than separated by a pattern.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse search, and it will be double ended if a forward/reverse search yields the same elements.
For iterating from the front, the split_terminator
method can be
used.
§Examples
let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
assert_eq!(v, ["B", "A"]);
let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
assert_eq!(v, ["", "B", "", "A"]);
let v: Vec<&str> = "A.B:C.D".rsplit_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["D", "C", "B", "A"]);
Run1.0.0 · sourcepub fn splitn<'a, P>(&'a self, n: usize, pat: P) -> SplitN<'a, P> ⓘwhere
P: Pattern<'a>,
pub fn splitn<'a, P>(&'a self, n: usize, pat: P) -> SplitN<'a, P> ⓘwhere
P: Pattern<'a>,
An iterator over substrings of the given string slice, separated by a
pattern, restricted to returning at most n
items.
If n
substrings are returned, the last substring (the n
th substring)
will contain the remainder of the string.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will not be double ended, because it is not efficient to support.
If the pattern allows a reverse search, the rsplitn
method can be
used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
assert_eq!(v, ["Mary", "had", "a little lambda"]);
let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
assert_eq!(v, ["lion", "", "tigerXleopard"]);
let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
assert_eq!(v, ["abcXdef"]);
let v: Vec<&str> = "".splitn(1, 'X').collect();
assert_eq!(v, [""]);
RunA more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["abc", "defXghi"]);
Run1.0.0 · sourcepub fn rsplitn<'a, P>(&'a self, n: usize, pat: P) -> RSplitN<'a, P> ⓘ
pub fn rsplitn<'a, P>(&'a self, n: usize, pat: P) -> RSplitN<'a, P> ⓘ
An iterator over substrings of this string slice, separated by a
pattern, starting from the end of the string, restricted to returning
at most n
items.
If n
substrings are returned, the last substring (the n
th substring)
will contain the remainder of the string.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will not be double ended, because it is not efficient to support.
For splitting from the front, the splitn
method can be used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
assert_eq!(v, ["lamb", "little", "Mary had a"]);
let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
assert_eq!(v, ["leopard", "tiger", "lionX"]);
let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
assert_eq!(v, ["leopard", "lion::tiger"]);
RunA more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "abc1def"]);
Run1.52.0 · sourcepub fn split_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)>where
P: Pattern<'a>,
pub fn split_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)>where
P: Pattern<'a>,
Splits the string on the first occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.
§Examples
assert_eq!("cfg".split_once('='), None);
assert_eq!("cfg=".split_once('='), Some(("cfg", "")));
assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));
Run1.52.0 · sourcepub fn rsplit_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)>
pub fn rsplit_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)>
Splits the string on the last occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.
§Examples
assert_eq!("cfg".rsplit_once('='), None);
assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));
Run1.2.0 · sourcepub fn matches<'a, P>(&'a self, pat: P) -> Matches<'a, P> ⓘwhere
P: Pattern<'a>,
pub fn matches<'a, P>(&'a self, pat: P) -> Matches<'a, P> ⓘwhere
P: Pattern<'a>,
An iterator over the disjoint matches of a pattern within the given string slice.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rmatches
method can be used.
§Examples
let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);
let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect();
assert_eq!(v, ["1", "2", "3"]);
Run1.2.0 · sourcepub fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P> ⓘ
pub fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P> ⓘ
An iterator over the disjoint matches of a pattern within this string slice, yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse
search, and it will be a DoubleEndedIterator
if a forward/reverse
search yields the same elements.
For iterating from the front, the matches
method can be used.
§Examples
let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);
let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect();
assert_eq!(v, ["3", "2", "1"]);
Run1.5.0 · sourcepub fn match_indices<'a, P>(&'a self, pat: P) -> MatchIndices<'a, P> ⓘwhere
P: Pattern<'a>,
pub fn match_indices<'a, P>(&'a self, pat: P) -> MatchIndices<'a, P> ⓘwhere
P: Pattern<'a>,
An iterator over the disjoint matches of a pattern within this string slice as well as the index that the match starts at.
For matches of pat
within self
that overlap, only the indices
corresponding to the first match are returned.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rmatch_indices
method can be used.
§Examples
let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect();
assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]);
let v: Vec<_> = "1abcabc2".match_indices("abc").collect();
assert_eq!(v, [(1, "abc"), (4, "abc")]);
let v: Vec<_> = "ababa".match_indices("aba").collect();
assert_eq!(v, [(0, "aba")]); // only the first `aba`
Run1.5.0 · sourcepub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P> ⓘ
pub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P> ⓘ
An iterator over the disjoint matches of a pattern within self
,
yielded in reverse order along with the index of the match.
For matches of pat
within self
that overlap, only the indices
corresponding to the last match are returned.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse
search, and it will be a DoubleEndedIterator
if a forward/reverse
search yields the same elements.
For iterating from the front, the match_indices
method can be used.
§Examples
let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect();
assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]);
let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect();
assert_eq!(v, [(4, "abc"), (1, "abc")]);
let v: Vec<_> = "ababa".rmatch_indices("aba").collect();
assert_eq!(v, [(2, "aba")]); // only the last `aba`
Run1.30.0 · sourcepub fn trim_start(&self) -> &str
pub fn trim_start(&self) -> &str
Returns a string slice with leading whitespace removed.
‘Whitespace’ is defined according to the terms of the Unicode Derived
Core Property White_Space
, which includes newlines.
§Text directionality
A string is a sequence of bytes. start
in this context means the first
position of that byte string; for a left-to-right language like English or
Russian, this will be left side, and for right-to-left languages like
Arabic or Hebrew, this will be the right side.
§Examples
Basic usage:
let s = "\n Hello\tworld\t\n";
assert_eq!("Hello\tworld\t\n", s.trim_start());
RunDirectionality:
let s = " English ";
assert!(Some('E') == s.trim_start().chars().next());
let s = " עברית ";
assert!(Some('ע') == s.trim_start().chars().next());
Run1.30.0 · sourcepub fn trim_end(&self) -> &str
pub fn trim_end(&self) -> &str
Returns a string slice with trailing whitespace removed.
‘Whitespace’ is defined according to the terms of the Unicode Derived
Core Property White_Space
, which includes newlines.
§Text directionality
A string is a sequence of bytes. end
in this context means the last
position of that byte string; for a left-to-right language like English or
Russian, this will be right side, and for right-to-left languages like
Arabic or Hebrew, this will be the left side.
§Examples
Basic usage:
let s = "\n Hello\tworld\t\n";
assert_eq!("\n Hello\tworld", s.trim_end());
RunDirectionality:
let s = " English ";
assert!(Some('h') == s.trim_end().chars().rev().next());
let s = " עברית ";
assert!(Some('ת') == s.trim_end().chars().rev().next());
Run1.0.0 · sourcepub fn trim_left(&self) -> &str
👎Deprecated since 1.33.0: superseded by trim_start
pub fn trim_left(&self) -> &str
trim_start
Returns a string slice with leading whitespace removed.
‘Whitespace’ is defined according to the terms of the Unicode Derived
Core Property White_Space
.
§Text directionality
A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.
§Examples
Basic usage:
let s = " Hello\tworld\t";
assert_eq!("Hello\tworld\t", s.trim_left());
RunDirectionality:
let s = " English";
assert!(Some('E') == s.trim_left().chars().next());
let s = " עברית";
assert!(Some('ע') == s.trim_left().chars().next());
Run1.0.0 · sourcepub fn trim_right(&self) -> &str
👎Deprecated since 1.33.0: superseded by trim_end
pub fn trim_right(&self) -> &str
trim_end
Returns a string slice with trailing whitespace removed.
‘Whitespace’ is defined according to the terms of the Unicode Derived
Core Property White_Space
.
§Text directionality
A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.
§Examples
Basic usage:
let s = " Hello\tworld\t";
assert_eq!(" Hello\tworld", s.trim_right());
RunDirectionality:
let s = "English ";
assert!(Some('h') == s.trim_right().chars().rev().next());
let s = "עברית ";
assert!(Some('ת') == s.trim_right().chars().rev().next());
Run1.0.0 · sourcepub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str
pub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str
Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.
The pattern can be a char
, a slice of char
s, or a function
or closure that determines if a character matches.
§Examples
Simple patterns:
assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");
RunA more complex pattern, using a closure:
assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");
Run1.30.0 · sourcepub fn trim_start_matches<'a, P>(&'a self, pat: P) -> &'a strwhere
P: Pattern<'a>,
pub fn trim_start_matches<'a, P>(&'a self, pat: P) -> &'a strwhere
P: Pattern<'a>,
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. start
in this context means the first
position of that byte string; for a left-to-right language like English or
Russian, this will be left side, and for right-to-left languages like
Arabic or Hebrew, this will be the right side.
§Examples
assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");
Run1.45.0 · sourcepub fn strip_prefix<'a, P>(&'a self, prefix: P) -> Option<&'a str>where
P: Pattern<'a>,
pub fn strip_prefix<'a, P>(&'a self, prefix: P) -> Option<&'a str>where
P: Pattern<'a>,
Returns a string slice with the prefix removed.
If the string starts with the pattern prefix
, returns the substring after the prefix,
wrapped in Some
. Unlike trim_start_matches
, this method removes the prefix exactly once.
If the string does not start with prefix
, returns None
.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar"));
assert_eq!("foo:bar".strip_prefix("bar"), None);
assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));
Run1.45.0 · sourcepub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str>
pub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str>
Returns a string slice with the suffix removed.
If the string ends with the pattern suffix
, returns the substring before the suffix,
wrapped in Some
. Unlike trim_end_matches
, this method removes the suffix exactly once.
If the string does not end with suffix
, returns None
.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar"));
assert_eq!("bar:foo".strip_suffix("bar"), None);
assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));
Run1.30.0 · sourcepub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a str
pub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a str
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. end
in this context means the last
position of that byte string; for a left-to-right language like English or
Russian, this will be right side, and for right-to-left languages like
Arabic or Hebrew, this will be the left side.
§Examples
Simple patterns:
assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");
RunA more complex pattern, using a closure:
assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");
Run1.0.0 · sourcepub fn trim_left_matches<'a, P>(&'a self, pat: P) -> &'a strwhere
P: Pattern<'a>,
👎Deprecated since 1.33.0: superseded by trim_start_matches
pub fn trim_left_matches<'a, P>(&'a self, pat: P) -> &'a strwhere
P: Pattern<'a>,
trim_start_matches
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.
§Examples
assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");
Run1.0.0 · sourcepub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str
👎Deprecated since 1.33.0: superseded by trim_end_matches
pub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str
trim_end_matches
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.
§Examples
Simple patterns:
assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");
RunA more complex pattern, using a closure:
assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");
Run1.0.0 · sourcepub fn parse<F>(&self) -> Result<F, <F as FromStr>::Err>where
F: FromStr,
pub fn parse<F>(&self) -> Result<F, <F as FromStr>::Err>where
F: FromStr,
Parses this string slice into another type.
Because parse
is so general, it can cause problems with type
inference. As such, parse
is one of the few times you’ll see
the syntax affectionately known as the ‘turbofish’: ::<>
. This
helps the inference algorithm understand specifically which type
you’re trying to parse into.
parse
can parse into any type that implements the FromStr
trait.
§Errors
Will return Err
if it’s not possible to parse this string slice into
the desired type.
§Examples
Basic usage
let four: u32 = "4".parse().unwrap();
assert_eq!(4, four);
RunUsing the ‘turbofish’ instead of annotating four
:
let four = "4".parse::<u32>();
assert_eq!(Ok(4), four);
RunFailing to parse:
let nope = "j".parse::<u32>();
assert!(nope.is_err());
Runsourcepub const fn as_ascii(&self) -> Option<&[AsciiChar]>
🔬This is a nightly-only experimental API. (ascii_char
#110998)
pub const fn as_ascii(&self) -> Option<&[AsciiChar]>
ascii_char
#110998)If this string slice is_ascii
, returns it as a slice
of ASCII characters, otherwise returns None
.
1.23.0 · sourcepub fn eq_ignore_ascii_case(&self, other: &str) -> bool
pub fn eq_ignore_ascii_case(&self, other: &str) -> bool
Checks that two strings are an ASCII case-insensitive match.
Same as to_ascii_lowercase(a) == to_ascii_lowercase(b)
,
but without allocating and copying temporaries.
§Examples
assert!("Ferris".eq_ignore_ascii_case("FERRIS"));
assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));
Run1.23.0 · sourcepub fn make_ascii_uppercase(&mut self)
pub fn make_ascii_uppercase(&mut self)
Converts this string to its ASCII upper case equivalent in-place.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To return a new uppercased value without modifying the existing one, use
to_ascii_uppercase()
.
§Examples
let mut s = String::from("Grüße, Jürgen ❤");
s.make_ascii_uppercase();
assert_eq!("GRüßE, JüRGEN ❤", s);
Run1.23.0 · sourcepub fn make_ascii_lowercase(&mut self)
pub fn make_ascii_lowercase(&mut self)
Converts this string to its ASCII lower case equivalent in-place.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To return a new lowercased value without modifying the existing one, use
to_ascii_lowercase()
.
§Examples
let mut s = String::from("GRÜßE, JÜRGEN ❤");
s.make_ascii_lowercase();
assert_eq!("grÜße, jÜrgen ❤", s);
Run1.80.0 (const: 1.80.0) · sourcepub const fn trim_ascii_start(&self) -> &str
pub const fn trim_ascii_start(&self) -> &str
Returns a string slice with leading ASCII whitespace removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(" \t \u{3000}hello world\n".trim_ascii_start(), "\u{3000}hello world\n");
assert_eq!(" ".trim_ascii_start(), "");
assert_eq!("".trim_ascii_start(), "");
Run1.80.0 (const: 1.80.0) · sourcepub const fn trim_ascii_end(&self) -> &str
pub const fn trim_ascii_end(&self) -> &str
Returns a string slice with trailing ASCII whitespace removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!("\r hello world\u{3000}\n ".trim_ascii_end(), "\r hello world\u{3000}");
assert_eq!(" ".trim_ascii_end(), "");
assert_eq!("".trim_ascii_end(), "");
Run1.80.0 (const: 1.80.0) · sourcepub const fn trim_ascii(&self) -> &str
pub const fn trim_ascii(&self) -> &str
Returns a string slice with leading and trailing ASCII whitespace removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!("\r hello world\n ".trim_ascii(), "hello world");
assert_eq!(" ".trim_ascii(), "");
assert_eq!("".trim_ascii(), "");
Run1.34.0 · sourcepub fn escape_debug(&self) -> EscapeDebug<'_> ⓘ
pub fn escape_debug(&self) -> EscapeDebug<'_> ⓘ
Return an iterator that escapes each char in self
with char::escape_debug
.
Note: only extended grapheme codepoints that begin the string will be escaped.
§Examples
As an iterator:
for c in "❤\n!".escape_debug() {
print!("{c}");
}
println!();
RunUsing println!
directly:
println!("{}", "❤\n!".escape_debug());
RunBoth are equivalent to:
println!("❤\\n!");
RunUsing to_string
:
assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");
Run1.34.0 · sourcepub fn escape_default(&self) -> EscapeDefault<'_> ⓘ
pub fn escape_default(&self) -> EscapeDefault<'_> ⓘ
Return an iterator that escapes each char in self
with char::escape_default
.
§Examples
As an iterator:
for c in "❤\n!".escape_default() {
print!("{c}");
}
println!();
RunUsing println!
directly:
println!("{}", "❤\n!".escape_default());
RunBoth are equivalent to:
println!("\\u{{2764}}\\n!");
RunUsing to_string
:
assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");
Run1.34.0 · sourcepub fn escape_unicode(&self) -> EscapeUnicode<'_> ⓘ
pub fn escape_unicode(&self) -> EscapeUnicode<'_> ⓘ
Return an iterator that escapes each char in self
with char::escape_unicode
.
§Examples
As an iterator:
for c in "❤\n!".escape_unicode() {
print!("{c}");
}
println!();
RunUsing println!
directly:
println!("{}", "❤\n!".escape_unicode());
RunBoth are equivalent to:
println!("\\u{{2764}}\\u{{a}}\\u{{21}}");
RunUsing to_string
:
assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");
Runsource§impl str
impl str
Methods for string slices.
1.0.0 · sourcepub fn replace<'a, P>(&'a self, from: P, to: &str) -> Stringwhere
P: Pattern<'a>,
pub fn replace<'a, P>(&'a self, from: P, to: &str) -> Stringwhere
P: Pattern<'a>,
Replaces all matches of a pattern with another string.
replace
creates a new String
, and copies the data from this string slice into it.
While doing so, it attempts to find matches of a pattern. If it finds any, it
replaces them with the replacement string slice.
§Examples
Basic usage:
let s = "this is old";
assert_eq!("this is new", s.replace("old", "new"));
assert_eq!("than an old", s.replace("is", "an"));
RunWhen the pattern doesn’t match, it returns this string slice as String
:
let s = "this is old";
assert_eq!(s, s.replace("cookie monster", "little lamb"));
Run1.16.0 · sourcepub fn replacen<'a, P>(&'a self, pat: P, to: &str, count: usize) -> Stringwhere
P: Pattern<'a>,
pub fn replacen<'a, P>(&'a self, pat: P, to: &str, count: usize) -> Stringwhere
P: Pattern<'a>,
Replaces first N matches of a pattern with another string.
replacen
creates a new String
, and copies the data from this string slice into it.
While doing so, it attempts to find matches of a pattern. If it finds any, it
replaces them with the replacement string slice at most count
times.
§Examples
Basic usage:
let s = "foo foo 123 foo";
assert_eq!("new new 123 foo", s.replacen("foo", "new", 2));
assert_eq!("faa fao 123 foo", s.replacen('o', "a", 3));
assert_eq!("foo foo new23 foo", s.replacen(char::is_numeric, "new", 1));
RunWhen the pattern doesn’t match, it returns this string slice as String
:
let s = "this is old";
assert_eq!(s, s.replacen("cookie monster", "little lamb", 10));
Run1.2.0 · sourcepub fn to_lowercase(&self) -> String
pub fn to_lowercase(&self) -> String
Returns the lowercase equivalent of this string slice, as a new String
.
‘Lowercase’ is defined according to the terms of the Unicode Derived Core Property
Lowercase
.
Since some characters can expand into multiple characters when changing
the case, this function returns a String
instead of modifying the
parameter in-place.
§Examples
Basic usage:
let s = "HELLO";
assert_eq!("hello", s.to_lowercase());
RunA tricky example, with sigma:
let sigma = "Σ";
assert_eq!("σ", sigma.to_lowercase());
// but at the end of a word, it's ς, not σ:
let odysseus = "ὈΔΥΣΣΕΎΣ";
assert_eq!("ὀδυσσεύς", odysseus.to_lowercase());
RunLanguages without case are not changed:
let new_year = "农历新年";
assert_eq!(new_year, new_year.to_lowercase());
Run1.2.0 · sourcepub fn to_uppercase(&self) -> String
pub fn to_uppercase(&self) -> String
Returns the uppercase equivalent of this string slice, as a new String
.
‘Uppercase’ is defined according to the terms of the Unicode Derived Core Property
Uppercase
.
Since some characters can expand into multiple characters when changing
the case, this function returns a String
instead of modifying the
parameter in-place.
§Examples
Basic usage:
let s = "hello";
assert_eq!("HELLO", s.to_uppercase());
RunScripts without case are not changed:
let new_year = "农历新年";
assert_eq!(new_year, new_year.to_uppercase());
RunOne character can become multiple:
let s = "tschüß";
assert_eq!("TSCHÜSS", s.to_uppercase());
Run1.4.0 · sourcepub fn into_string(self: Box<str>) -> String
pub fn into_string(self: Box<str>) -> String
1.16.0 · sourcepub fn repeat(&self, n: usize) -> String
pub fn repeat(&self, n: usize) -> String
1.23.0 · sourcepub fn to_ascii_uppercase(&self) -> String
pub fn to_ascii_uppercase(&self) -> String
Returns a copy of this string where each character is mapped to its ASCII upper case equivalent.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To uppercase the value in-place, use make_ascii_uppercase
.
To uppercase ASCII characters in addition to non-ASCII characters, use
to_uppercase
.
§Examples
let s = "Grüße, Jürgen ❤";
assert_eq!("GRüßE, JüRGEN ❤", s.to_ascii_uppercase());
Run1.23.0 · sourcepub fn to_ascii_lowercase(&self) -> String
pub fn to_ascii_lowercase(&self) -> String
Returns a copy of this string where each character is mapped to its ASCII lower case equivalent.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To lowercase the value in-place, use make_ascii_lowercase
.
To lowercase ASCII characters in addition to non-ASCII characters, use
to_lowercase
.
§Examples
let s = "Grüße, Jürgen ❤";
assert_eq!("grüße, jürgen ❤", s.to_ascii_lowercase());
RunTrait Implementations§
1.0.0 · source§impl Add<&str> for String
impl Add<&str> for String
Implements the
operator for concatenating two strings.
This consumes the String
on the left-hand side and re-uses its buffer (growing it if
necessary). This is done to avoid allocating a new String
and copying the entire contents on
every operation, which would lead to O(n^2) running time when building an n-byte string by
repeated concatenation.
The string on the right-hand side is only borrowed; its contents are copied into the returned
String
.
§Examples
Concatenating two String
s takes the first by value and borrows the second:
let a = String::from("hello");
let b = String::from(" world");
let c = a &b;
// `a` is moved and can no longer be used here.
RunIf you want to keep using the first String
, you can clone it and append to the clone instead:
let a = String::from("hello");
let b = String::from(" world");
let c = a.clone() &b;
// `a` is still valid here.
RunConcatenating &str
slices can be done by converting the first to a String
:
let a = "hello";
let b = " world";
let c = a.to_string() b;
Run1.14.0 · source§impl<'a> AddAssign<&'a str> for Cow<'a, str>
impl<'a> AddAssign<&'a str> for Cow<'a, str>
source§fn add_assign(&mut self, rhs: &'a str)
fn add_assign(&mut self, rhs: &'a str)
=
operation. Read more1.12.0 · source§impl AddAssign<&str> for String
impl AddAssign<&str> for String
Implements the =
operator for appending to a String
.
This has the same behavior as the push_str
method.
source§fn add_assign(&mut self, other: &str)
fn add_assign(&mut self, other: &str)
=
operation. Read more1.0.0 · source§impl AsciiExt for str
impl AsciiExt for str
§type Owned = String
type Owned = String
source§fn is_ascii(&self) -> bool
fn is_ascii(&self) -> bool
source§fn to_ascii_uppercase(&self) -> Self::Owned
fn to_ascii_uppercase(&self) -> Self::Owned
source§fn to_ascii_lowercase(&self) -> Self::Owned
fn to_ascii_lowercase(&self) -> Self::Owned
source§fn eq_ignore_ascii_case(&self, o: &Self) -> bool
fn eq_ignore_ascii_case(&self, o: &Self) -> bool
source§fn make_ascii_uppercase(&mut self)
fn make_ascii_uppercase(&mut self)
source§fn make_ascii_lowercase(&mut self)
fn make_ascii_lowercase(&mut self)
1.36.0 · source§impl BorrowMut<str> for String
impl BorrowMut<str> for String
source§fn borrow_mut(&mut self) -> &mut str
fn borrow_mut(&mut self) -> &mut str
source§impl<S> Concat<str> for [S]
impl<S> Concat<str> for [S]
Note: str
in Concat<str>
is not meaningful here.
This type parameter of the trait only exists to enable another impl.
1.0.0 · source§impl !Error for &str
impl !Error for &str
1.30.0 · source§fn source(&self) -> Option<&(dyn Error 'static)>
fn source(&self) -> Option<&(dyn Error 'static)>
1.0.0 · source§fn description(&self) -> &str
fn description(&self) -> &str
1.0.0 · source§impl<'a> Extend<&'a str> for String
impl<'a> Extend<&'a str> for String
1.6.0 · source§impl<'a> From<&str> for Box<dyn Error 'a>
impl<'a> From<&str> for Box<dyn Error 'a>
1.0.0 · source§impl<'a> From<&str> for Box<dyn Error Sync Send 'a>
impl<'a> From<&str> for Box<dyn Error Sync Send 'a>
1.45.0 · source§impl From<Cow<'_, str>> for Box<str>
impl From<Cow<'_, str>> for Box<str>
source§fn from(cow: Cow<'_, str>) -> Box<str>
fn from(cow: Cow<'_, str>) -> Box<str>
Converts a Cow<'_, str>
into a Box<str>
When cow
is the Cow::Borrowed
variant, this
conversion allocates on the heap and copies the
underlying str
. Otherwise, it will try to reuse the owned
String
’s allocation.
§Examples
use std::borrow::Cow;
let unboxed = Cow::Borrowed("hello");
let boxed: Box<str> = Box::from(unboxed);
println!("{boxed}");
Runlet unboxed = Cow::Owned("hello".to_string());
let boxed: Box<str> = Box::from(unboxed);
println!("{boxed}");
Run1.0.0 · source§impl<'a> FromIterator<&'a str> for String
impl<'a> FromIterator<&'a str> for String
1.0.0 · source§impl Ord for str
impl Ord for str
Implements ordering of strings.
Strings are ordered lexicographically by their byte values. This orders Unicode code
points based on their positions in the code charts. This is not necessarily the same as
“alphabetical” order, which varies by language and locale. Sorting strings according to
culturally-accepted standards requires locale-specific data that is outside the scope of
the str
type.
1.29.0 · source§impl PartialEq<&str> for OsString
impl PartialEq<&str> for OsString
1.0.0 · source§impl<'a, 'b> PartialEq<Cow<'a, str>> for &'b str
impl<'a, 'b> PartialEq<Cow<'a, str>> for &'b str
1.0.0 · source§impl<'a, 'b> PartialEq<Cow<'a, str>> for str
impl<'a, 'b> PartialEq<Cow<'a, str>> for str
1.0.0 · source§impl PartialEq<OsStr> for str
impl PartialEq<OsStr> for str
1.29.0 · source§impl<'a> PartialEq<OsString> for &'a str
impl<'a> PartialEq<OsString> for &'a str
1.0.0 · source§impl PartialEq<OsString> for str
impl PartialEq<OsString> for str
1.0.0 · source§impl PartialOrd<str> for OsStr
impl PartialOrd<str> for OsStr
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
self
and other
) and is used by the <=
operator. Read more1.0.0 · source§impl PartialOrd<str> for OsString
impl PartialOrd<str> for OsString
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
self
and other
) and is used by the <=
operator. Read more1.0.0 · source§impl PartialOrd for str
impl PartialOrd for str
Implements comparison operations on strings.
Strings are compared lexicographically by their byte values. This compares Unicode code
points based on their positions in the code charts. This is not necessarily the same as
“alphabetical” order, which varies by language and locale. Comparing strings according to
culturally-accepted standards requires locale-specific data that is outside the scope of
the str
type.
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
self
and other
) and is used by the <=
operator. Read moresource§impl<'a, 'b> Pattern<'a> for &'b str
impl<'a, 'b> Pattern<'a> for &'b str
Non-allocating substring search.
Will handle the pattern ""
as returning empty matches at each character
boundary.
§Examples
assert_eq!("Hello world".find("world"), Some(6));
Runsource§fn is_prefix_of(self, haystack: &'a str) -> bool
🔬This is a nightly-only experimental API. (pattern
#27721)
fn is_prefix_of(self, haystack: &'a str) -> bool
pattern
#27721)Checks whether the pattern matches at the front of the haystack.
source§fn is_contained_in(self, haystack: &'a str) -> bool
🔬This is a nightly-only experimental API. (pattern
#27721)
fn is_contained_in(self, haystack: &'a str) -> bool
pattern
#27721)Checks whether the pattern matches anywhere in the haystack
source§fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str>
🔬This is a nightly-only experimental API. (pattern
#27721)
fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str>
pattern
#27721)Removes the pattern from the front of haystack, if it matches.
source§fn is_suffix_of(self, haystack: &'a str) -> bool
🔬This is a nightly-only experimental API. (pattern
#27721)
fn is_suffix_of(self, haystack: &'a str) -> bool
pattern
#27721)Checks whether the pattern matches at the back of the haystack.
source§fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str>
🔬This is a nightly-only experimental API. (pattern
#27721)
fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str>
pattern
#27721)Removes the pattern from the back of haystack, if it matches.
§type Searcher = StrSearcher<'a, 'b>
type Searcher = StrSearcher<'a, 'b>
pattern
#27721)source§fn into_searcher(self, haystack: &'a str) -> StrSearcher<'a, 'b>
fn into_searcher(self, haystack: &'a str) -> StrSearcher<'a, 'b>
pattern
#27721)self
and the haystack
to search in.1.73.0 · source§impl SliceIndex<str> for (Bound<usize>, Bound<usize>)
impl SliceIndex<str> for (Bound<usize>, Bound<usize>)
Implements substring slicing for arbitrary bounds.
Returns a slice of the given string bounded by the byte indices provided by each bound.
This operation is O(1).
§Panics
Panics if begin
or end
(if it exists and once adjusted for
inclusion/exclusion) does not point to the starting byte offset of
a character (as defined by is_char_boundary
), if begin > end
, or if
end > len
.
source§fn get(self, slice: &str) -> Option<&str>
fn get(self, slice: &str) -> Option<&str>
slice_index_methods
)source§fn get_mut(self, slice: &mut str) -> Option<&mut str>
fn get_mut(self, slice: &mut str) -> Option<&mut str>
slice_index_methods
)source§unsafe fn get_unchecked(self, slice: *const str) -> *const str
unsafe fn get_unchecked(self, slice: *const str) -> *const str
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut str
unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut str
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§impl SliceIndex<str> for Range<usize>
impl SliceIndex<str> for Range<usize>
source§fn get(self, slice: &str) -> Option<&<Range<usize> as SliceIndex<str>>::Output>
fn get(self, slice: &str) -> Option<&<Range<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <Range<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <Range<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <Range<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <Range<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <Range<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <Range<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.1.20.0 (const: unstable) · source§impl SliceIndex<str> for Range<usize>
impl SliceIndex<str> for Range<usize>
Implements substring slicing with syntax &self[begin .. end]
or &mut self[begin .. end]
.
Returns a slice of the given string from the byte range
[begin
, end
).
This operation is O(1).
Prior to 1.20.0, these indexing operations were still supported by
direct implementation of Index
and IndexMut
.
§Panics
Panics if begin
or end
does not point to the starting byte offset of
a character (as defined by is_char_boundary
), if begin > end
, or if
end > len
.
§Examples
let s = "Löwe 老虎 Léopard";
assert_eq!(&s[0 .. 1], "L");
assert_eq!(&s[1 .. 9], "öwe 老");
// these will panic:
// byte 2 lies within `ö`:
// &s[2 ..3];
// byte 8 lies within `老`
// &s[1 .. 8];
// byte 100 is outside the string
// &s[3 .. 100];
Runsource§fn get(self, slice: &str) -> Option<&<Range<usize> as SliceIndex<str>>::Output>
fn get(self, slice: &str) -> Option<&<Range<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <Range<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <Range<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <Range<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <Range<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <Range<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <Range<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.1.20.0 (const: unstable) · source§impl SliceIndex<str> for RangeFrom<usize>
impl SliceIndex<str> for RangeFrom<usize>
Implements substring slicing with syntax &self[begin ..]
or &mut self[begin ..]
.
Returns a slice of the given string from the byte range [begin
, len
).
Equivalent to &self[begin .. len]
or &mut self[begin .. len]
.
This operation is O(1).
Prior to 1.20.0, these indexing operations were still supported by
direct implementation of Index
and IndexMut
.
§Panics
Panics if begin
does not point to the starting byte offset of
a character (as defined by is_char_boundary
), or if begin > len
.
source§fn get(
self,
slice: &str,
) -> Option<&<RangeFrom<usize> as SliceIndex<str>>::Output>
fn get( self, slice: &str, ) -> Option<&<RangeFrom<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <RangeFrom<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <RangeFrom<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <RangeFrom<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <RangeFrom<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <RangeFrom<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <RangeFrom<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§impl SliceIndex<str> for RangeFrom<usize>
impl SliceIndex<str> for RangeFrom<usize>
source§fn get(
self,
slice: &str,
) -> Option<&<RangeFrom<usize> as SliceIndex<str>>::Output>
fn get( self, slice: &str, ) -> Option<&<RangeFrom<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <RangeFrom<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <RangeFrom<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <RangeFrom<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <RangeFrom<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <RangeFrom<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <RangeFrom<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.1.20.0 (const: unstable) · source§impl SliceIndex<str> for RangeFull
impl SliceIndex<str> for RangeFull
Implements substring slicing with syntax &self[..]
or &mut self[..]
.
Returns a slice of the whole string, i.e., returns &self
or &mut self
. Equivalent to &self[0 .. len]
or &mut self[0 .. len]
. Unlike
other indexing operations, this can never panic.
This operation is O(1).
Prior to 1.20.0, these indexing operations were still supported by
direct implementation of Index
and IndexMut
.
Equivalent to &self[0 .. len]
or &mut self[0 .. len]
.
source§fn get(self, slice: &str) -> Option<&<RangeFull as SliceIndex<str>>::Output>
fn get(self, slice: &str) -> Option<&<RangeFull as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <RangeFull as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <RangeFull as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <RangeFull as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <RangeFull as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <RangeFull as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <RangeFull as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.1.26.0 (const: unstable) · source§impl SliceIndex<str> for RangeInclusive<usize>
impl SliceIndex<str> for RangeInclusive<usize>
Implements substring slicing with syntax &self[begin ..= end]
or &mut self[begin ..= end]
.
Returns a slice of the given string from the byte range
[begin
, end
]. Equivalent to &self [begin .. end 1]
or &mut self[begin .. end 1]
, except if end
has the maximum value for
usize
.
This operation is O(1).
§Panics
Panics if begin
does not point to the starting byte offset of
a character (as defined by is_char_boundary
), if end
does not point
to the ending byte offset of a character (end 1
is either a starting
byte offset or equal to len
), if begin > end
, or if end >= len
.
source§fn get(
self,
slice: &str,
) -> Option<&<RangeInclusive<usize> as SliceIndex<str>>::Output>
fn get( self, slice: &str, ) -> Option<&<RangeInclusive<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <RangeInclusive<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <RangeInclusive<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <RangeInclusive<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <RangeInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <RangeInclusive<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <RangeInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§fn index(
self,
slice: &str,
) -> &<RangeInclusive<usize> as SliceIndex<str>>::Output ⓘ
fn index( self, slice: &str, ) -> &<RangeInclusive<usize> as SliceIndex<str>>::Output ⓘ
slice_index_methods
)source§fn index_mut(
self,
slice: &mut str,
) -> &mut <RangeInclusive<usize> as SliceIndex<str>>::Output ⓘ
fn index_mut( self, slice: &mut str, ) -> &mut <RangeInclusive<usize> as SliceIndex<str>>::Output ⓘ
slice_index_methods
)source§impl SliceIndex<str> for RangeInclusive<usize>
impl SliceIndex<str> for RangeInclusive<usize>
source§fn get(
self,
slice: &str,
) -> Option<&<RangeInclusive<usize> as SliceIndex<str>>::Output>
fn get( self, slice: &str, ) -> Option<&<RangeInclusive<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <RangeInclusive<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <RangeInclusive<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <RangeInclusive<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <RangeInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <RangeInclusive<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <RangeInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§fn index(
self,
slice: &str,
) -> &<RangeInclusive<usize> as SliceIndex<str>>::Output
fn index( self, slice: &str, ) -> &<RangeInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)source§fn index_mut(
self,
slice: &mut str,
) -> &mut <RangeInclusive<usize> as SliceIndex<str>>::Output
fn index_mut( self, slice: &mut str, ) -> &mut <RangeInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)1.20.0 (const: unstable) · source§impl SliceIndex<str> for RangeTo<usize>
impl SliceIndex<str> for RangeTo<usize>
Implements substring slicing with syntax &self[.. end]
or &mut self[.. end]
.
Returns a slice of the given string from the byte range [0, end
).
Equivalent to &self[0 .. end]
or &mut self[0 .. end]
.
This operation is O(1).
Prior to 1.20.0, these indexing operations were still supported by
direct implementation of Index
and IndexMut
.
§Panics
Panics if end
does not point to the starting byte offset of a
character (as defined by is_char_boundary
), or if end > len
.
source§fn get(
self,
slice: &str,
) -> Option<&<RangeTo<usize> as SliceIndex<str>>::Output>
fn get( self, slice: &str, ) -> Option<&<RangeTo<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <RangeTo<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <RangeTo<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <RangeTo<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <RangeTo<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <RangeTo<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <RangeTo<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.1.26.0 (const: unstable) · source§impl SliceIndex<str> for RangeToInclusive<usize>
impl SliceIndex<str> for RangeToInclusive<usize>
Implements substring slicing with syntax &self[..= end]
or &mut self[..= end]
.
Returns a slice of the given string from the byte range [0, end
].
Equivalent to &self [0 .. end 1]
, except if end
has the maximum
value for usize
.
This operation is O(1).
§Panics
Panics if end
does not point to the ending byte offset of a character
(end 1
is either a starting byte offset as defined by
is_char_boundary
, or equal to len
), or if end >= len
.
source§fn get(
self,
slice: &str,
) -> Option<&<RangeToInclusive<usize> as SliceIndex<str>>::Output>
fn get( self, slice: &str, ) -> Option<&<RangeToInclusive<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut str,
) -> Option<&mut <RangeToInclusive<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str, ) -> Option<&mut <RangeToInclusive<usize> as SliceIndex<str>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const str,
) -> *const <RangeToInclusive<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str, ) -> *const <RangeToInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut str,
) -> *mut <RangeToInclusive<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str, ) -> *mut <RangeToInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting pointer is not used.source§fn index(
self,
slice: &str,
) -> &<RangeToInclusive<usize> as SliceIndex<str>>::Output
fn index( self, slice: &str, ) -> &<RangeToInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)source§fn index_mut(
self,
slice: &mut str,
) -> &mut <RangeToInclusive<usize> as SliceIndex<str>>::Output
fn index_mut( self, slice: &mut str, ) -> &mut <RangeToInclusive<usize> as SliceIndex<str>>::Output
slice_index_methods
)1.0.0 · source§impl ToSocketAddrs for str
impl ToSocketAddrs for str
§type Iter = IntoIter<SocketAddr>
type Iter = IntoIter<SocketAddr>
source§fn to_socket_addrs(&self) -> Result<IntoIter<SocketAddr>>
fn to_socket_addrs(&self) -> Result<IntoIter<SocketAddr>>
SocketAddr
s. Read more