pub struct Percent(_, _);Expand description
Human readable percentage.
Percent::from input can be:
The default Percent::from implementation will print 2 decimal numbers.
Anything lower than 0.01 is rounded down to 0.00.
This can be changed by using different functions when initially
creating the Percent, or converting an existing Percent, for example:
let f0 = Percent::new_0(3.0);
let f2 = Percent::from(3.0);
let f3 = Percent::new_3(3.0);
let f4 = Percent::new_4(3.0);
assert!(f0 == "3%");
assert!(f2 == "3.00%");
assert!(f3 == "3.000%");
assert!(f4 == "3.0000%");Cloning
Clone may be expensive:
// Probably cheap (stack allocated string).
let a = Percent::from(100.0);
let b = a.clone();
// Probably expensive (heap allocated string).
let a = Percent::from(f64::MAX);
let b = a.clone();The actual string used internally is not a String,
but a CompactString so that any string 24 bytes (12 bytes on 32-bit) or less are stack allocated instead of heap allocated.
The documentation will still refer to the inner string as a String. Anything returned will also be a String.
Exceptions
f64::NANoutputsNANf64::INFINITYoutputsINFINITY
To disable checks for these, (you are sure you don’t have NaN’s), enable the ignore_nan_inf feature flag.
Math
These operators are overloaded. They will always output a new Self:
Add +Sub -Div /Mul *Rem %
They can either be:
- Combined with another
Self:Percent::from(1.0) + Percent::from(1.0) - Or with the inner number itself:
Percent::from(1.0) + 1.0
They also have the same panic!() behavior on overflow as the normal ones, because internally,
it is just calling .inner() $OPERATOR $NUMBER.
assert!(Percent::from(10.0) + 10.0 == Percent::from(20.0));
assert!(Percent::from(10.0) - 10.0 == Percent::from(0.0));
assert!(Percent::from(10.0) / 10.0 == Percent::from(1.0));
assert!(Percent::from(10.0) * 10.0 == Percent::from(100.0));
assert!(Percent::from(10.0) % 10.0 == Percent::from(0.0));Overflow example (floats don’t panic in this case):
let n = Percent::from(f64::MAX) + f64::MAX;
assert!(n.inner().is_infinite());Examples
assert!(Percent::zero() == "0.00%");
assert!(Percent::unknown() == "?.??%");
assert!(Percent::from(0.001) == "0.00%");
assert!(Percent::from(0.1) == "0.10%");
assert!(Percent::from(1.0) == "1.00%");
assert!(Percent::from(100.0) == "100.00%");
assert!(Percent::from(1_000.0) == "1,000.00%");
assert!(Percent::from(1_u64) == "1.00%");
assert!(Percent::from(1_000_u64) == "1,000.00%");
assert!(Percent::from(10_000_u64) == "10,000.00%");
assert!(Percent::from(-1_i64) == "-1.00%");
assert!(Percent::from(-1_000_i64) == "-1,000.00%");
assert!(Percent::from(-10_000_i64) == "-10,000.00%");Implementations§
source§impl Percent
impl Percent
sourcepub fn into_string(self) -> String
pub fn into_string(self) -> String
sourcepub fn head_tail(&self, head: usize, tail: usize) -> String
pub fn head_tail(&self, head: usize, tail: usize) -> String
Return the first head bytes and last tail
bytes of this string separated with ....
Since all readable types happen to only contain
ASCII characters, all char’s are equal to 1 byte.
let date = Date::from_str("2021-12-11").unwrap();
assert!(date.head_tail(3, 2) == "202...11");
assert!(date.head_tail(3, 3) == "202...-11");
assert!(date.head_tail(3, 5) == "202...12-11");sourcepub fn inf() -> Self
pub fn inf() -> Self
Returns a Self with the f64 value of f64::INFINITY.
The String is set to ∞.
sourcepub fn new_0(f: f64) -> Self
pub fn new_0(f: f64) -> Self
Same as Self::from but with no floating point on the inner String.
The inner f64 stays the same as the input.
This does not round up or down, it completely ignores the floating point.
Examples
| Input | String Output |
|---|---|
| 0.0 | 0% |
| 50.123 | 50% |
| 100.1 | 100% |
sourcepub fn new_1(f: f64) -> Self
pub fn new_1(f: f64) -> Self
Same as Percent::from but with 1 floating point.
sourcepub fn new_3(f: f64) -> Self
pub fn new_3(f: f64) -> Self
Same as Percent::from but with 3 floating point.
sourcepub fn new_4(f: f64) -> Self
pub fn new_4(f: f64) -> Self
Same as Percent::from but with 4 floating point.
sourcepub fn new_5(f: f64) -> Self
pub fn new_5(f: f64) -> Self
Same as Percent::from but with 5 floating point.
sourcepub fn new_6(f: f64) -> Self
pub fn new_6(f: f64) -> Self
Same as Percent::from but with 6 floating point.
sourcepub fn new_7(f: f64) -> Self
pub fn new_7(f: f64) -> Self
Same as Percent::from but with 7 floating point.
sourcepub fn new_8(f: f64) -> Self
pub fn new_8(f: f64) -> Self
Same as Percent::from but with 8 floating point.
sourcepub fn new_9(f: f64) -> Self
pub fn new_9(f: f64) -> Self
Same as Percent::from but with 9 floating point.
sourcepub fn new_10(f: f64) -> Self
pub fn new_10(f: f64) -> Self
Same as Percent::from but with 10 floating point.
sourcepub fn new_11(f: f64) -> Self
pub fn new_11(f: f64) -> Self
Same as Percent::from but with 11 floating point.
sourcepub fn new_12(f: f64) -> Self
pub fn new_12(f: f64) -> Self
Same as Percent::from but with 12 floating point.
sourcepub fn new_13(f: f64) -> Self
pub fn new_13(f: f64) -> Self
Same as Percent::from but with 13 floating point.
sourcepub fn new_14(f: f64) -> Self
pub fn new_14(f: f64) -> Self
Same as Percent::from but with 14 floating point.
sourcepub fn new_15(f: f64) -> Self
pub fn new_15(f: f64) -> Self
Same as Percent::from but with 15 floating point.
sourcepub fn new_16(f: f64) -> Self
pub fn new_16(f: f64) -> Self
Same as Percent::from but with 16 floating point.
sourcepub fn new_17(f: f64) -> Self
pub fn new_17(f: f64) -> Self
Same as Percent::from but with 17 floating point.
sourcepub fn new_18(f: f64) -> Self
pub fn new_18(f: f64) -> Self
Same as Percent::from but with 18 floating point.
Methods from Deref<Target = str>§
1.0.0 · sourcepub fn len(&self) -> usize
pub fn len(&self) -> usize
Returns the length of self.
This length is in bytes, not chars or graphemes. In other words,
it might not be what a human considers the length of the string.
Examples
Basic usage:
let len = "foo".len();
assert_eq!(3, len);
assert_eq!("ƒoo".len(), 4); // fancy f!
assert_eq!("ƒoo".chars().count(), 3);1.0.0 · sourcepub fn is_empty(&self) -> bool
pub fn is_empty(&self) -> bool
Returns true if self has a length of zero bytes.
Examples
Basic usage:
let s = "";
assert!(s.is_empty());
let s = "not empty";
assert!(!s.is_empty());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));sourcepub fn floor_char_boundary(&self, index: usize) -> usize
🔬This is a nightly-only experimental API. (round_char_boundary)
pub fn floor_char_boundary(&self, index: usize) -> usize
round_char_boundary)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], "❤️🧡");sourcepub fn ceil_char_boundary(&self, index: usize) -> usize
🔬This is a nightly-only experimental API. (round_char_boundary)
pub fn ceil_char_boundary(&self, index: usize) -> usize
round_char_boundary)Finds the closest x not below index where is_char_boundary(x) is true.
This method is the natural complement to floor_char_boundary. See that method
for more details.
Panics
Panics if index > self.len().
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], "❤️🧡💛");1.0.0 · sourcepub fn as_ptr(&self) -> *const u8
pub 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
Basic usage:
let s = "Hello";
let ptr = s.as_ptr();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());1.20.0 · 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));
}1.0.0 · 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:
beginmust not exceedend.beginandendmust be byte positions within the string slice.beginandendmust lie on UTF-8 sequence boundaries.
Examples
Basic usage:
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));
}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.
Examples
Basic usage:
let s = "Per Martin-Löf";
let (first, last) = s.split_at(3);
assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);1.0.0 · sourcepub fn chars(&self) -> Chars<'_>
pub 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 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());Remember, chars 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());1.0.0 · sourcepub fn char_indices(&self) -> CharIndices<'_>
pub 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:
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 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 last 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());1.0.0 · 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
Basic usage:
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());1.1.0 · 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());All 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());If 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);1.34.0 · 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());All 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());If 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);1.0.0 · 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.
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\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:
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());1.0.0 · 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<'_>
Returns an iterator of u16 over the string encoded as UTF-16.
Examples
Basic usage:
let text = "Zażółć gęślą jaźń";
let utf8_len = text.len();
let utf16_len = text.encode_utf16().count();
assert!(utf16_len <= utf8_len);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 chars, or a
function or closure that determines if a character matches.
Examples
Basic usage:
let bananas = "bananas";
assert!(bananas.contains("nana"));
assert!(!bananas.contains("apples"));1.0.0 · 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, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
Basic usage:
let bananas = "bananas";
assert!(bananas.starts_with("bana"));
assert!(!bananas.starts_with("nana"));1.0.0 · sourcepub fn ends_with<'a, P>(&'a self, pat: P) -> boolwhere
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn ends_with<'a, P>(&'a self, pat: P) -> boolwhere P: Pattern<'a>, <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
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 chars, or a
function or closure that determines if a character matches.
Examples
Basic usage:
let bananas = "bananas";
assert!(bananas.ends_with("anas"));
assert!(!bananas.ends_with("nana"));1.0.0 · 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 chars, 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));More 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));Not finding the pattern:
let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];
assert_eq!(s.find(x), None);1.0.0 · sourcepub fn rfind<'a, P>(&'a self, pat: P) -> Option<usize>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rfind<'a, P>(&'a self, pat: P) -> Option<usize>where P: Pattern<'a>, <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
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 chars, 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));More 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));Not finding the pattern:
let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];
assert_eq!(s.rfind(x), None);1.0.0 · 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 chars, 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"]);If 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"]);A more complex pattern, using a closure:
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:
let x = "||||a||b|c".to_string();
let d: Vec<_> = x.split('|').collect();
assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);Contiguous separators are separated by the empty string.
let x = "(///)".to_string();
let d: Vec<_> = x.split('/').collect();
assert_eq!(d, &["(", "", "", ")"]);Separators at the start or end of a string are neighbored by empty strings.
let d: Vec<_> = "010".split("0").collect();
assert_eq!(d, &["", "1", ""]);When 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", ""]);Contiguous 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"]);It does not give you:
assert_eq!(d, &["a", "b", "c"]);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 chars, 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."]);If 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"]);1.0.0 · sourcepub fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P>where P: Pattern<'a>, <P as Pattern<'a>>::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, a slice of chars, 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"]);A more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "def", "abc"]);1.0.0 · 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 chars, 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
Basic usage:
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"]);1.0.0 · sourcepub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P>where P: Pattern<'a>, <P as Pattern<'a>>::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 &str, char, a slice of chars, 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"]);1.0.0 · 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 nth substring)
will contain the remainder of the string.
The pattern can be a &str, char, a slice of chars, 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, [""]);A more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["abc", "defXghi"]);1.0.0 · sourcepub fn rsplitn<'a, P>(&'a self, n: usize, pat: P) -> RSplitN<'a, P>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rsplitn<'a, P>(&'a self, n: usize, pat: P) -> RSplitN<'a, P>where P: Pattern<'a>, <P as Pattern<'a>>::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 n items.
If n substrings are returned, the last substring (the nth substring)
will contain the remainder of the string.
The pattern can be a &str, char, a slice of chars, 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"]);A more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "abc1def"]);1.52.0 · 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")));1.52.0 · sourcepub fn rsplit_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rsplit_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)>where P: Pattern<'a>, <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
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")));1.2.0 · 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 chars, 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
Basic usage:
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"]);1.2.0 · sourcepub fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P>where P: Pattern<'a>, <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
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 chars, 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
Basic usage:
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"]);1.5.0 · 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 chars, 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
Basic usage:
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`1.5.0 · sourcepub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P>where P: Pattern<'a>, <P as Pattern<'a>>::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, a slice of chars, 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
Basic usage:
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`1.0.0 · sourcepub fn trim(&self) -> &str
pub 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, which includes newlines.
Examples
Basic usage:
let s = "\n Hello\tworld\t\n";
assert_eq!("Hello\tworld", s.trim());1.30.0 · 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());Directionality:
let s = " English ";
assert!(Some('E') == s.trim_start().chars().next());
let s = " עברית ";
assert!(Some('ע') == s.trim_start().chars().next());1.30.0 · 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());Directionality:
let s = " English ";
assert!(Some('h') == s.trim_end().chars().rev().next());
let s = " עברית ";
assert!(Some('ת') == s.trim_end().chars().rev().next());1.0.0 · sourcepub fn trim_left(&self) -> &str
👎Deprecated since 1.33.0: superseded by trim_start
pub fn trim_left(&self) -> &str
trim_startReturns 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());Directionality:
let s = " English";
assert!(Some('E') == s.trim_left().chars().next());
let s = " עברית";
assert!(Some('ע') == s.trim_left().chars().next());1.0.0 · sourcepub fn trim_right(&self) -> &str
👎Deprecated since 1.33.0: superseded by trim_end
pub fn trim_right(&self) -> &str
trim_endReturns 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());Directionality:
let s = "English ";
assert!(Some('h') == s.trim_right().chars().rev().next());
let s = "עברית ";
assert!(Some('ת') == s.trim_right().chars().rev().next());1.0.0 · sourcepub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a strwhere
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: DoubleEndedSearcher<'a>,
pub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a strwhere P: Pattern<'a>, <P as Pattern<'a>>::Searcher: DoubleEndedSearcher<'a>,
Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.
The pattern can be a char, a slice of chars, 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");A more complex pattern, using a closure:
assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");1.30.0 · 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 chars, 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
Basic usage:
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");1.45.0 · 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 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 chars, 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"));1.45.0 · sourcepub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str>where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str>where P: Pattern<'a>, <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
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 chars, 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"));1.30.0 · sourcepub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a strwhere
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a strwhere P: Pattern<'a>, <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, 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");A more complex pattern, using a closure:
assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");1.0.0 · 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_matchesReturns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, 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
Basic usage:
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");1.0.0 · sourcepub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a strwhere
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
👎Deprecated since 1.33.0: superseded by trim_end_matches
pub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a strwhere P: Pattern<'a>, <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
trim_end_matchesReturns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, 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");A more complex pattern, using a closure:
assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");1.0.0 · 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);Using the ‘turbofish’ instead of annotating four:
let four = "4".parse::<u32>();
assert_eq!(Ok(4), four);Failing to parse:
let nope = "j".parse::<u32>();
assert!(nope.is_err());1.23.0 · sourcepub fn is_ascii(&self) -> bool
pub fn is_ascii(&self) -> bool
Checks if all characters in this string are within the ASCII range.
Examples
let ascii = "hello!\n";
let non_ascii = "Grüße, Jürgen ❤";
assert!(ascii.is_ascii());
assert!(!non_ascii.is_ascii());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"));1.34.0 · 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!();Using println! directly:
println!("{}", "❤\n!".escape_debug());Both are equivalent to:
println!("❤\\n!");Using to_string:
assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");1.34.0 · 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!();Using println! directly:
println!("{}", "❤\n!".escape_default());Both are equivalent to:
println!("\\u{{2764}}\\n!");Using to_string:
assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");1.34.0 · 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!();Using println! directly:
println!("{}", "❤\n!".escape_unicode());Both are equivalent to:
println!("\\u{{2764}}\\u{{a}}\\u{{21}}");Using to_string:
assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");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"));When 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"));1.16.0 · 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));When 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));1.2.0 · 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());A 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());Languages without case are not changed:
let new_year = "农历新年";
assert_eq!(new_year, new_year.to_lowercase());1.2.0 · 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());Scripts without case are not changed:
let new_year = "农历新年";
assert_eq!(new_year, new_year.to_uppercase());One character can become multiple:
let s = "tschüß";
assert_eq!("TSCHÜSS", s.to_uppercase());1.16.0 · sourcepub fn repeat(&self, n: usize) -> String
pub fn repeat(&self, n: usize) -> String
Creates a new String by repeating a string n times.
Panics
This function will panic if the capacity would overflow.
Examples
Basic usage:
assert_eq!("abc".repeat(4), String::from("abcabcabcabc"));A panic upon overflow:
// this will panic at runtime
let huge = "0123456789abcdef".repeat(usize::MAX);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());1.23.0 · 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());Trait Implementations§
source§impl<'de> Deserialize<'de> for Percent
impl<'de> Deserialize<'de> for Percent
source§fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>where
__D: Deserializer<'de>,
fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>where __D: Deserializer<'de>,
source§impl PartialEq<&Percent> for f64
impl PartialEq<&Percent> for f64
source§impl PartialEq<&Percent> for str
impl PartialEq<&Percent> for str
source§impl PartialEq<&str> for Percent
impl PartialEq<&str> for Percent
source§impl PartialEq<Percent> for Percent
impl PartialEq<Percent> for Percent
source§impl PartialEq<Percent> for f64
impl PartialEq<Percent> for f64
source§impl PartialEq<Percent> for str
impl PartialEq<Percent> for str
source§impl PartialOrd<Percent> for Percent
impl PartialOrd<Percent> for Percent
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 moreimpl StructuralPartialEq for Percent
Auto Trait Implementations§
impl RefUnwindSafe for Percent
impl Send for Percent
impl Sync for Percent
impl Unpin for Percent
impl UnwindSafe for Percent
Blanket Implementations§
source§impl<S> ParseFormatted for Swhere
S: AsRef<str>,
impl<S> ParseFormatted for Swhere S: AsRef<str>,
source§fn parse_formatted<F, N>(&self, format: &F) -> Result<N, Error>where
F: Format,
N: FromFormattedStr,
fn parse_formatted<F, N>(&self, format: &F) -> Result<N, Error>where F: Format, N: FromFormattedStr,
self (typically a formatted string) into a number (see Examples above).source§impl<T> ToCompactString for Twhere
T: Display,
impl<T> ToCompactString for Twhere T: Display,
source§fn to_compact_string(&self) -> CompactString
fn to_compact_string(&self) -> CompactString
CompactString. Read more