Primitive Type str [−]
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.
Strings slices are always valid UTF-8.
This documentation describes a number of methods and trait implementations
on the str type. For technical reasons, there is additional, separate
documentation in the std::str module as well.
Examples
String literals are string slices:
fn main() { let hello = "Hello, world!"; // with an explicit type annotation let hello: &'static str = "Hello, world!"; }let hello = "Hello, world!"; // with an explicit type annotation let hello: &'static str = "Hello, world!";
They are 'static because they're stored directly in the final binary, and
so will be valid for the 'static duration.
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 thirteen bytes assert_eq!(19, len); // We can re-build a str out of ptr and len. This is all unsafe becuase // 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));
Methods
impl str
Methods for string slices.
fn len(&self) -> usize
Returns the length of self.
This length is in bytes, not chars or graphemes. In other words,
it may not be what a human considers the length of the string.
Examples
Basic usage:
fn main() { let len = "foo".len(); assert_eq!(3, len); let len = "ƒoo".len(); // fancy f! assert_eq!(4, len); }let len = "foo".len(); assert_eq!(3, len); let len = "ƒoo".len(); // fancy f! assert_eq!(4, len);
fn is_empty(&self) -> bool
Returns true if this slice has a length of zero bytes.
Examples
Basic usage:
fn main() { let s = ""; assert!(s.is_empty()); let s = "not empty"; assert!(!s.is_empty()); }let s = ""; assert!(s.is_empty()); let s = "not empty"; assert!(!s.is_empty());
fn is_char_boundary(&self, index: usize) -> bool
str_char #27754): it is unclear whether this method pulls its weight with the existence of the char_indices iterator or this method may want to be replaced with checked slicing
Checks that index-th byte lies at the start and/or end of a
UTF-8 code point sequence.
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
#![feature(str_char)] fn main() { 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)); }#![feature(str_char)] 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));
fn as_bytes(&self) -> &[u8]
Converts a string slice to a byte slice.
Examples
Basic usage:
fn main() { let bytes = "bors".as_bytes(); assert_eq!(b"bors", bytes); }let bytes = "bors".as_bytes(); assert_eq!(b"bors", bytes);
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.
Examples
Basic usage:
fn main() { let s = "Hello"; let ptr = s.as_ptr(); }let s = "Hello"; let ptr = s.as_ptr();
unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str
Creates a string slice from another string slice, bypassing safety checks.
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 satisifed:
beginmust come beforeend.beginandendmust be bye positions within the string slice.beginandendmust lie on UTF-8 sequence boundaries.
Examples
Basic usage:
fn main() { 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)); } }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)); }
unsafe fn slice_mut_unchecked(&mut self, begin: usize, end: usize) -> &mut str
Creates a string slice from another string slice, bypassing safety checks.
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 satisifed:
beginmust come beforeend.beginandendmust be bye positions within the string slice.beginandendmust lie on UTF-8 sequence boundaries.
fn char_range_at(&self, start: usize) -> CharRange
str_char #27754): often replaced by char_indices, this method may be removed in favor of just char_at() or eventually removed altogether
Given a byte position, returns the next char and its index.
Panics
If i is greater than or equal to the length of the string.
If i is not the index of the beginning of a valid UTF-8 sequence.
Examples
This example manually iterates through the code points of a string;
this should normally be
done by .chars() or .char_indices().
#![feature(str_char)] use std::str::CharRange; let s = "中华Việt Nam"; let mut i = 0; while i < s.len() { let CharRange {ch, next} = s.char_range_at(i); println!("{}: {}", i, ch); i = next; }
This outputs:
0: 中
3: 华
6: V
7: i
8: e
9:
11:
13: t
14:
15: N
16: a
17: m
fn char_range_at_reverse(&self, start: usize) -> CharRange
str_char #27754): often replaced by char_indices, this method may be removed in favor of just char_at_reverse() or eventually removed altogether
Given a byte position, returns the previous char and its position.
Note that Unicode has many features, such as combining marks, ligatures, and direction marks, that need to be taken into account to correctly reverse a string.
Returns 0 for next index if called on start index 0.
Panics
If i is greater than the length of the string.
If i is not an index following a valid UTF-8 sequence.
Examples
This example manually iterates through the code points of a string;
this should normally be
done by .chars().rev() or .char_indices().
#![feature(str_char)] use std::str::CharRange; let s = "中华Việt Nam"; let mut i = s.len(); while i > 0 { let CharRange {ch, next} = s.char_range_at_reverse(i); println!("{}: {}", i, ch); i = next; }
This outputs:
18: m
17: a
16: N
15:
14: t
13:
11:
9: e
8: i
7: V
6: 华
3: 中
fn char_at(&self, i: usize) -> char
str_char #27754): frequently replaced by the chars() iterator, this method may be removed or possibly renamed in the future; it is normally replaced by chars/char_indices iterators or by getting the first char from a subslice
Given a byte position, returns the char at that position.
Panics
If i is greater than or equal to the length of the string.
If i is not the index of the beginning of a valid UTF-8 sequence.
Examples
#![feature(str_char)] fn main() { let s = "abπc"; assert_eq!(s.char_at(1), 'b'); assert_eq!(s.char_at(2), 'π'); assert_eq!(s.char_at(4), 'c'); }#![feature(str_char)] let s = "abπc"; assert_eq!(s.char_at(1), 'b'); assert_eq!(s.char_at(2), 'π'); assert_eq!(s.char_at(4), 'c');
fn char_at_reverse(&self, i: usize) -> char
str_char #27754): see char_at for more details, but reverse semantics are also somewhat unclear, especially with which cases generate panics
Given a byte position, returns the char at that position, counting
from the end.
Panics
If i is greater than the length of the string.
If i is not an index following a valid UTF-8 sequence.
Examples
#![feature(str_char)] fn main() { let s = "abπc"; assert_eq!(s.char_at_reverse(1), 'a'); assert_eq!(s.char_at_reverse(2), 'b'); assert_eq!(s.char_at_reverse(3), 'π'); }#![feature(str_char)] let s = "abπc"; assert_eq!(s.char_at_reverse(1), 'a'); assert_eq!(s.char_at_reverse(2), 'b'); assert_eq!(s.char_at_reverse(3), 'π');
fn slice_shift_char(&self) -> Option<(char, &str)>
str_char #27754): awaiting conventions about shifting and slices and may not be warranted with the existence of the chars and/or char_indices iterators
Retrieves the first char from a &str and returns it.
Note that a single Unicode character (grapheme cluster)
can be composed of multiple chars.
This does not allocate a new string; instead, it returns a slice that points one code point beyond the code point that was shifted.
None is returned if the slice is empty.
Examples
#![feature(str_char)] fn main() { let s = "Łódź"; // \u{141}o\u{301}dz\u{301} let (c, s1) = s.slice_shift_char().unwrap(); assert_eq!(c, 'Ł'); assert_eq!(s1, "ódź"); let (c, s2) = s1.slice_shift_char().unwrap(); assert_eq!(c, 'o'); assert_eq!(s2, "\u{301}dz\u{301}"); }#![feature(str_char)] let s = "Łódź"; // \u{141}o\u{301}dz\u{301} let (c, s1) = s.slice_shift_char().unwrap(); assert_eq!(c, 'Ł'); assert_eq!(s1, "ódź"); let (c, s2) = s1.slice_shift_char().unwrap(); assert_eq!(c, 'o'); assert_eq!(s2, "\u{301}dz\u{301}");
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
beyond the last code point of the string slice.
Examples
Basic usage:
fn main() { let s = "Per Martin-Löf"; let (first, last) = s.split_at(3); assert_eq!("Per", first); assert_eq!(" Martin-Löf", last); }let s = "Per Martin-Löf"; let (first, last) = s.split_at(3); assert_eq!("Per", first); assert_eq!(" Martin-Löf", last);
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
beyond the last code point of the string slice.
Examples
Basic usage:
fn main() { let s = "Per Martin-Löf"; let (first, last) = s.split_at(3); assert_eq!("Per", first); assert_eq!(" Martin-Löf", last); }let s = "Per Martin-Löf"; let (first, last) = s.split_at(3); assert_eq!("Per", first); assert_eq!(" Martin-Löf", last);
fn chars(&self) -> Chars
Returns an iterator over the chars 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 may not match your idea of what a 'character' is. Iteration
over grapheme clusters may be what you actually want.
Examples
Basic usage:
fn main() { 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()); }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());
Remember, chars may not match your human 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());
fn char_indices(&self) -> CharIndices
Returns an iterator over the chars 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 chars, as well as their byte positions.
The iterator yields tuples. The position is first, the char is
second.
Examples
Basic usage:
fn main() { 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()); }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());
Remember, chars may not match your human intuition about characters:
let y = "y̆"; let mut char_indices = y.char_indices(); assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆') assert_eq!(Some((1, '\u{0306}')), char_indices.next()); assert_eq!(None, char_indices.next());
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
Basic usage:
fn main() { 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()); }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());
fn split_whitespace(&self) -> SplitWhitespace
Split 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.
Examples
Basic usage:
fn main() { 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()); }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());
All kinds of whitespace are considered:
fn main() { 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()); }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());
fn lines(&self) -> Lines
An iterator over the lines of a string, as string slices.
Lines are ended with either a newline (\n) or a carriage return with
a line feed (\r\n).
The final line ending is optional.
Examples
Basic usage:
fn main() { let text = "foo\r\nbar\n\nbaz\n"; 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()); }let text = "foo\r\nbar\n\nbaz\n"; 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());
The final line ending isn't required:
fn main() { 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()); }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());
fn lines_any(&self) -> LinesAny
: use lines() instead now
An iterator over the lines of a string.
fn utf16_units(&self) -> Utf16Units
Returns an iterator of u16 over the string encoded as UTF-16.
fn contains<'a, P>(&'a self, pat: P) -> bool where P: Pattern<'a>
Returns true if the given &str is a sub-slice of this string slice.
Returns false if it's not.
Examples
Basic usage:
fn main() { let bananas = "bananas"; assert!(bananas.contains("nana")); assert!(!bananas.contains("apples")); }let bananas = "bananas"; assert!(bananas.contains("nana")); assert!(!bananas.contains("apples"));
fn starts_with<'a, P>(&'a self, pat: P) -> bool where P: Pattern<'a>
Returns true if the given &str is a prefix of this string slice.
Returns false if it's not.
Examples
Basic usage:
fn main() { let bananas = "bananas"; assert!(bananas.starts_with("bana")); assert!(!bananas.starts_with("nana")); }let bananas = "bananas"; assert!(bananas.starts_with("bana")); assert!(!bananas.starts_with("nana"));
fn ends_with<'a, P>(&'a self, pat: P) -> bool where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
Returns true if the given &str is a suffix of this string slice.
Returns false if not.
Examples
Basic usage:
fn main() { let bananas = "bananas"; assert!(bananas.ends_with("anas")); assert!(!bananas.ends_with("nana")); }let bananas = "bananas"; assert!(bananas.ends_with("anas")); assert!(!bananas.ends_with("nana"));
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, or a closure that determines if
a character matches.
Examples
Simple patterns:
fn main() { let s = "Löwe 老虎 Léopard"; assert_eq!(s.find('L'), Some(0)); assert_eq!(s.find('é'), Some(14)); assert_eq!(s.find("Léopard"), Some(13)); }let s = "Löwe 老虎 Léopard"; assert_eq!(s.find('L'), Some(0)); assert_eq!(s.find('é'), Some(14)); assert_eq!(s.find("Léopard"), Some(13));
More complex patterns with closures:
fn main() { let s = "Löwe 老虎 Léopard"; assert_eq!(s.find(char::is_whitespace), Some(5)); assert_eq!(s.find(char::is_lowercase), Some(1)); }let s = "Löwe 老虎 Léopard"; assert_eq!(s.find(char::is_whitespace), Some(5)); assert_eq!(s.find(char::is_lowercase), Some(1));
Not finding the pattern:
fn main() { let s = "Löwe 老虎 Léopard"; let x: &[_] = &['1', '2']; assert_eq!(s.find(x), None); }let s = "Löwe 老虎 Léopard"; let x: &[_] = &['1', '2']; assert_eq!(s.find(x), None);
fn rfind<'a, P>(&'a self, pat: P) -> Option<usize> where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
Returns the byte index of the last character of this string slice that matches the pattern.
Returns None if the pattern doesn't match.
The pattern can be a &str, char, or a closure that determines if
a character matches.
Examples
Simple patterns:
fn main() { let s = "Löwe 老虎 Léopard"; assert_eq!(s.rfind('L'), Some(13)); assert_eq!(s.rfind('é'), Some(14)); }let s = "Löwe 老虎 Léopard"; assert_eq!(s.rfind('L'), Some(13)); assert_eq!(s.rfind('é'), Some(14));
More complex patterns with closures:
fn main() { let s = "Löwe 老虎 Léopard"; assert_eq!(s.rfind(char::is_whitespace), Some(12)); assert_eq!(s.rfind(char::is_lowercase), Some(20)); }let s = "Löwe 老虎 Léopard"; assert_eq!(s.rfind(char::is_whitespace), Some(12)); assert_eq!(s.rfind(char::is_lowercase), Some(20));
Not finding the pattern:
fn main() { let s = "Löwe 老虎 Léopard"; let x: &[_] = &['1', '2']; assert_eq!(s.rfind(x), None); }let s = "Löwe 老虎 Léopard"; let x: &[_] = &['1', '2']; assert_eq!(s.rfind(x), None);
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, or a closure that determines the
split.
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, eg, 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:
fn main() { 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"]); }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"]);
A more complex pattern, using a closure:
fn main() { let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect(); assert_eq!(v, ["abc", "def", "ghi"]); }let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect(); assert_eq!(v, ["abc", "def", "ghi"]);
If a string contains multiple contiguous separators, you will end up with empty strings in the output:
fn main() { let x = "||||a||b|c".to_string(); let d: Vec<_> = x.split('|').collect(); assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]); }let x = "||||a||b|c".to_string(); let d: Vec<_> = x.split('|').collect(); assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
This can lead to possibly surprising behavior when whitespace is used as the separator. This code is correct:
fn main() { let x = " a b c".to_string(); let d: Vec<_> = x.split(' ').collect(); assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]); }let x = " a b c".to_string(); let d: Vec<_> = x.split(' ').collect(); assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
It does not give you:
fn main() { assert_eq!(d, &["a", "b", "c"]); }assert_eq!(d, &["a", "b", "c"]);
Use split_whitespace() for this behavior.
fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P> where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
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, or a closure that determines the
split.
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:
fn main() { 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"]); }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"]);
A more complex pattern, using a closure:
fn main() { let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect(); assert_eq!(v, ["ghi", "def", "abc"]); }let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect(); assert_eq!(v, ["ghi", "def", "abc"]);
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, or a closure that determines the
split.
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, eg, 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
Basic usage:
fn main() { 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.".split_terminator('.').collect(); assert_eq!(v, ["A", "B"]); let v: Vec<&str> = "A..B..".split_terminator(".").collect(); assert_eq!(v, ["A", "", "B", ""]);
fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P> where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
An iterator over substrings of self, separated by characters
matched by a pattern and yielded in reverse order.
The pattern can be a simple &str, char, or a closure that
determines the split.
Additional libraries might provide more complex patterns like
regular expressions.
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
fn main() { 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.".rsplit_terminator('.').collect(); assert_eq!(v, ["B", "A"]); let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect(); assert_eq!(v, ["", "B", "", "A"]);
fn splitn<'a, P>(&'a self, count: 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 count items.
The last element returned, if any, will contain the remainder of the string slice.
The pattern can be a &str, char, or a closure that determines the
split.
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:
fn main() { 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, [""]); }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, [""]);
A more complex pattern, using a closure:
fn main() { let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect(); assert_eq!(v, ["abc", "defXghi"]); }let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect(); assert_eq!(v, ["abc", "defXghi"]);
fn rsplitn<'a, P>(&'a self, count: usize, pat: P) -> RSplitN<'a, P> where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
An iterator over substrings of this string slice, separated by a
pattern, starting from the end of the string, restricted to returning
at most count items.
The last element returned, if any, will contain the remainder of the string slice.
The pattern can be a &str, char, or a closure that
determines the split.
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:
fn main() { 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"]); }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"]);
A more complex pattern, using a closure:
fn main() { let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect(); assert_eq!(v, ["ghi", "abc1def"]); }let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect(); assert_eq!(v, ["ghi", "abc1def"]);
fn matches<'a, P>(&'a self, pat: P) -> Matches<'a, P> where P: Pattern<'a>
An iterator over the matches of a pattern within the given string slice.
The pattern can be a &str, char, or a 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, eg, 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
Basic usage:
fn main() { 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"]); }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"]);
fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P> where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
An iterator over the matches of a pattern within this string slice, yielded in reverse order.
The pattern can be a &str, char, or a 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
Basic usage:
fn main() { 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"]); }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"]);
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, or a 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, eg, 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
Basic usage:
fn main() { 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` }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`
fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P> where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
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, or a 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
Basic usage:
fn main() { 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` }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`
fn trim(&self) -> &str
Returns a string slice with leading and trailing whitespace removed.
'Whitespace' is defined according to the terms of the Unicode Derived
Core Property White_Space.
Examples
Basic usage:
fn main() { let s = " Hello\tworld\t"; assert_eq!("Hello\tworld", s.trim()); }let s = " Hello\tworld\t"; assert_eq!("Hello\tworld", s.trim());
fn trim_left(&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.
Examples
Basic usage:
fn main() { let s = " Hello\tworld\t"; assert_eq!("Hello\tworld\t", s.trim_left()); }let s = " Hello\tworld\t"; assert_eq!("Hello\tworld\t", s.trim_left());
fn trim_right(&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.
Examples
Basic usage:
fn main() { let s = " Hello\tworld\t"; assert_eq!(" Hello\tworld", s.trim_right()); }let s = " Hello\tworld\t"; assert_eq!(" Hello\tworld", s.trim_right());
fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>
Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, or a closure that determines
if a character matches.
Examples
Simple patterns:
fn main() { 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"); }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");
A more complex pattern, using a closure:
fn main() { assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar"); }assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");
fn trim_left_matches<'a, P>(&'a self, pat: P) -> &'a str where P: Pattern<'a>
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str, char, or a closure that determines if
a character matches.
Examples
Basic usage:
fn main() { 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"); }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");
fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str where P: Pattern<'a>, P::Searcher: ReverseSearcher<'a>
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, or a closure that
determines if a character matches.
Examples
Simple patterns:
fn main() { 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"); }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");
A more complex pattern, using a closure:
fn main() { assert_eq!("1fooX".trim_left_matches(|c| c == '1' || c == 'X'), "fooX"); }assert_eq!("1fooX".trim_left_matches(|c| c == '1' || c == 'X'), "fooX");
fn parse<F>(&self) -> Result<F, F::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 any type that implements the FromStr trait.
Failure
Will return Err if it's not possible to parse this string slice into
the desired type.
Example
Basic usage
fn main() { let four: u32 = "4".parse().unwrap(); assert_eq!(4, four); }let four: u32 = "4".parse().unwrap(); assert_eq!(4, four);
Using the 'turbofish' instead of annotationg four:
let four = "4".parse::<u32>(); assert_eq!(Ok(4), four);
Failing to parse:
fn main() { let nope = "j".parse::<u32>(); assert!(nope.is_err()); }let nope = "j".parse::<u32>(); assert!(nope.is_err());
fn replace(&self, from: &str, to: &str) -> String
Replaces all occurrences of one string with another.
replace creates a new String, and copies the data from this string slice into it.
While doing so, it attempts to find a sub-&str. If it finds it, it replaces it with
the replacement string slice.
Examples
Basic usage:
fn main() { let s = "this is old"; assert_eq!("this is new", s.replace("old", "new")); }let s = "this is old"; assert_eq!("this is new", s.replace("old", "new"));
When a &str isn't found:
let s = "this is old"; assert_eq!(s, s.replace("cookie monster", "little lamb"));
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.
Examples
Basic usage:
fn main() { let s = "HELLO"; assert_eq!("hello", s.to_lowercase()); }let s = "HELLO"; assert_eq!("hello", s.to_lowercase());
A tricky example, with sigma:
fn main() { 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()); }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());
Languages without case are not changed:
fn main() { let new_year = "农历新年"; assert_eq!(new_year, new_year.to_lowercase()); }let new_year = "农历新年"; assert_eq!(new_year, new_year.to_lowercase());
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.
Examples
Basic usage:
fn main() { let s = "hello"; assert_eq!("HELLO", s.to_uppercase()); }let s = "hello"; assert_eq!("HELLO", s.to_uppercase());
Scripts without case are not changed:
fn main() { let new_year = "农历新年"; assert_eq!(new_year, new_year.to_uppercase()); }let new_year = "农历新年"; assert_eq!(new_year, new_year.to_uppercase());
fn escape_default(&self) -> String
Escapes each char in s with char::escape_default.
fn escape_unicode(&self) -> String
Escapes each char in s with char::escape_unicode.
fn into_string(self: Box<str>) -> String
Converts a Box<str> into a String without copying or allocating.
Examples
Basic usage:
fn main() { let string = String::from("birthday gift"); let boxed_str = string.clone().into_boxed_str(); assert_eq!(boxed_str.into_string(), string); }let string = String::from("birthday gift"); let boxed_str = string.clone().into_boxed_str(); assert_eq!(boxed_str.into_string(), string);
Trait Implementations
impl AsRef<str> for str
impl Repr<Slice<u8>> for str
fn repr(&self) -> T
impl<'a, 'b> Pattern<'a> for &'b str
Non-allocating substring search.
Will handle the pattern "" as returning empty matches at each character
boundary.
type Searcher = StrSearcher<'a, 'b>
fn into_searcher(self, haystack: &'a str) -> StrSearcher<'a, 'b>
fn is_prefix_of(self, haystack: &'a str) -> bool
fn is_suffix_of(self, haystack: &'a str) -> bool
fn is_contained_in(self, haystack: &'a str) -> bool
impl Ord for str
impl PartialEq<str> for str
impl Eq for str
impl PartialOrd<str> for str
fn partial_cmp(&self, other: &str) -> Option<Ordering>
fn lt(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
fn gt(&self, other: &Rhs) -> bool
fn ge(&self, other: &Rhs) -> bool
impl Index<Range<usize>> for str
Returns a slice of the given string from the byte range
[begin..end).
This operation is O(1).
Panics when begin and end do not point to valid characters
or point beyond the last character of the string.
Examples
fn main() { 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]; }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];
impl IndexMut<Range<usize>> for str
Returns a mutable slice of the given string from the byte range
[begin..end).
impl Index<RangeTo<usize>> for str
Returns a slice of the string from the beginning to byte
end.
Equivalent to self[0 .. end].
Panics when end does not point to a valid character, or is
out of bounds.
impl IndexMut<RangeTo<usize>> for str
Returns a mutable slice of the string from the beginning to byte
end.
impl Index<RangeFrom<usize>> for str
Returns a slice of the string from begin to its end.
Equivalent to self[begin .. self.len()].
Panics when begin does not point to a valid character, or is
out of bounds.
impl IndexMut<RangeFrom<usize>> for str
Returns a slice of the string from begin to its end.