Struct std::string::String
[−]
[src]
pub struct String {
// some fields omitted
}A growable string stored as a UTF-8 encoded buffer.
Methods
impl String
fn new() -> String
Creates a new string buffer initialized with the empty string.
Examples
fn main() { let mut s = String::new(); }let mut s = String::new();
fn with_capacity(capacity: usize) -> String
Creates a new string buffer with the given capacity.
The string will be able to hold exactly capacity bytes without
reallocating. If capacity is 0, the string will not allocate.
Examples
fn main() { let mut s = String::with_capacity(10); }let mut s = String::with_capacity(10);
fn from_utf8(vec: Vec<u8>) -> Result<String, FromUtf8Error>
Converts a vector of bytes to a String.
A string slice (&str) is made of bytes (u8), and a vector of bytes
(Vec<u8>) is made of bytes, so this function converts between the
two. Not all byte slices are valid Strings, however: String
requires that it is valid UTF-8. from_utf8() checks to ensure that
the bytes are valid UTF-8, and then does the conversion.
If you are sure that the byte slice is valid UTF-8, and you don't want
to incur the overhead of the validity check, there is an unsafe version
of this function, from_utf8_unchecked(), which has the
same behavior but skips the check.
This method will take care to not copy the vector, for efficiency's sake.
If you need a &str instead of a String, consider
str::from_utf8().
Failure
Returns Err if the slice is not UTF-8 with a description as to why the
provided bytes are not UTF-8. The vector you moved in is also included.
Examples
Basic usage:
fn main() { // some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so just use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart); }// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so just use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart);
Incorrect bytes:
fn main() { // some invalid bytes, in a vector let sparkle_heart = vec![0, 159, 146, 150]; assert!(String::from_utf8(sparkle_heart).is_err()); }// some invalid bytes, in a vector let sparkle_heart = vec![0, 159, 146, 150]; assert!(String::from_utf8(sparkle_heart).is_err());
See the docs for FromUtf8Error for more details on what you
can do with this error.
fn from_utf8_lossy(v: &'a [u8]) -> Cow<'a, str>
Converts a slice of bytes to a String, including invalid characters.
A string slice (&str) is made of bytes (u8), and a slice of bytes
(&[u8]) is made of bytes, so this function converts between the two.
Not all byte slices are valid string slices, however: &str requires
that it is valid UTF-8. During this conversion, from_utf8_lossy()
will replace any invalid UTF-8 sequences with
U+FFFD REPLACEMENT CHARACTER, which looks like this: �
If you are sure that the byte slice is valid UTF-8, and you don't want
to incur the overhead of the conversion, there is an unsafe version
of this function, from_utf8_unchecked(), which has the
same behavior but skips the checks.
If you need a &str instead of a String, consider
str::from_utf8().
Examples
Basic usage:
fn main() { // some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so just use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart); }// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so just use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart);
Incorrect bytes:
fn main() { // some invalid bytes let input = b"Hello \xF0\x90\x80World"; let output = String::from_utf8_lossy(input); assert_eq!("Hello �World", output); }// some invalid bytes let input = b"Hello \xF0\x90\x80World"; let output = String::from_utf8_lossy(input); assert_eq!("Hello �World", output);
fn from_utf16(v: &[u16]) -> Result<String, FromUtf16Error>
Decode a UTF-16 encoded vector v into a String, returning None
if v contains any invalid data.
Examples
fn main() { // 𝄞music let mut v = &mut [0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063]; assert_eq!(String::from_utf16(v).unwrap(), "𝄞music".to_string()); // 𝄞mu<invalid>ic v[4] = 0xD800; assert!(String::from_utf16(v).is_err()); }// 𝄞music let mut v = &mut [0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063]; assert_eq!(String::from_utf16(v).unwrap(), "𝄞music".to_string()); // 𝄞mu<invalid>ic v[4] = 0xD800; assert!(String::from_utf16(v).is_err());
fn from_utf16_lossy(v: &[u16]) -> String
Decode a UTF-16 encoded vector v into a string, replacing
invalid data with the replacement character (U+FFFD).
Examples
fn main() { // 𝄞mus<invalid>ic<invalid> let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834]; assert_eq!(String::from_utf16_lossy(v), "𝄞mus\u{FFFD}ic\u{FFFD}".to_string()); }// 𝄞mus<invalid>ic<invalid> let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834]; assert_eq!(String::from_utf16_lossy(v), "𝄞mus\u{FFFD}ic\u{FFFD}".to_string());
unsafe fn from_raw_parts(buf: *mut u8, length: usize, capacity: usize) -> String
Creates a new String from a length, capacity, and pointer.
Safety
This is very unsafe because:
- We call
Vec::from_raw_partsto get aVec<u8>. Therefore, this function inherits all of its unsafety, see its documentation for the invariants it expects, they also apply to this function. - We assume that the
Veccontains valid UTF-8.
unsafe fn from_utf8_unchecked(bytes: Vec<u8>) -> String
Converts a vector of bytes to a String without checking that the
string contains valid UTF-8.
See the safe version, from_utf8(), for more.
Safety
This function is unsafe because it does not check that the bytes passed to
it are valid UTF-8. If this constraint is violated, undefined behavior
results, as the rest of Rust assumes that Strings are valid UTF-8.
Examples
Basic usage:
fn main() { // some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; let sparkle_heart = unsafe { String::from_utf8_unchecked(sparkle_heart) }; assert_eq!("💖", sparkle_heart); }// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; let sparkle_heart = unsafe { String::from_utf8_unchecked(sparkle_heart) }; assert_eq!("💖", sparkle_heart);
fn into_bytes(self) -> Vec<u8>
Returns the underlying byte buffer, encoded as UTF-8.
Examples
fn main() { let s = String::from("hello"); let bytes = s.into_bytes(); assert_eq!(bytes, [104, 101, 108, 108, 111]); }let s = String::from("hello"); let bytes = s.into_bytes(); assert_eq!(bytes, [104, 101, 108, 108, 111]);
fn as_str(&self) -> &str
Extracts a string slice containing the entire string.
fn push_str(&mut self, string: &str)
Pushes the given string onto this string buffer.
Examples
fn main() { let mut s = String::from("foo"); s.push_str("bar"); assert_eq!(s, "foobar"); }let mut s = String::from("foo"); s.push_str("bar"); assert_eq!(s, "foobar");
fn capacity(&self) -> usize
Returns the number of bytes that this string buffer can hold without reallocating.
Examples
fn main() { let s = String::with_capacity(10); assert!(s.capacity() >= 10); }let s = String::with_capacity(10); assert!(s.capacity() >= 10);
fn reserve(&mut self, additional: usize)
Reserves capacity for at least additional more bytes to be inserted
in the given String. The collection may reserve more space to avoid
frequent reallocations.
Panics
Panics if the new capacity overflows usize.
Examples
fn main() { let mut s = String::new(); s.reserve(10); assert!(s.capacity() >= 10); }let mut s = String::new(); s.reserve(10); assert!(s.capacity() >= 10);
fn reserve_exact(&mut self, additional: usize)
Reserves the minimum capacity for exactly additional more bytes to be
inserted in the given String. Does nothing if the capacity is already
sufficient.
Note that the allocator may give the collection more space than it
requests. Therefore capacity can not be relied upon to be precisely
minimal. Prefer reserve if future insertions are expected.
Panics
Panics if the new capacity overflows usize.
Examples
fn main() { let mut s = String::new(); s.reserve_exact(10); assert!(s.capacity() >= 10); }let mut s = String::new(); s.reserve_exact(10); assert!(s.capacity() >= 10);
fn shrink_to_fit(&mut self)
Shrinks the capacity of this string buffer to match its length.
Examples
fn main() { let mut s = String::from("foo"); s.reserve(100); assert!(s.capacity() >= 100); s.shrink_to_fit(); assert_eq!(s.capacity(), 3); }let mut s = String::from("foo"); s.reserve(100); assert!(s.capacity() >= 100); s.shrink_to_fit(); assert_eq!(s.capacity(), 3);
fn push(&mut self, ch: char)
Adds the given character to the end of the string.
Examples
fn main() { let mut s = String::from("abc"); s.push('1'); s.push('2'); s.push('3'); assert_eq!(s, "abc123"); }let mut s = String::from("abc"); s.push('1'); s.push('2'); s.push('3'); assert_eq!(s, "abc123");
fn as_bytes(&self) -> &[u8]
Works with the underlying buffer as a byte slice.
Examples
fn main() { let s = String::from("hello"); assert_eq!(s.as_bytes(), [104, 101, 108, 108, 111]); }let s = String::from("hello"); assert_eq!(s.as_bytes(), [104, 101, 108, 108, 111]);
fn truncate(&mut self, new_len: usize)
Shortens a string to the specified length.
Panics
Panics if new_len > current length,
or if new_len is not a character boundary.
Examples
fn main() { let mut s = String::from("hello"); s.truncate(2); assert_eq!(s, "he"); }let mut s = String::from("hello"); s.truncate(2); assert_eq!(s, "he");
fn pop(&mut self) -> Option<char>
Removes the last character from the string buffer and returns it.
Returns None if this string buffer is empty.
Examples
fn main() { let mut s = String::from("foo"); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('f')); assert_eq!(s.pop(), None); }let mut s = String::from("foo"); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('f')); assert_eq!(s.pop(), None);
fn remove(&mut self, idx: usize) -> char
Removes the character from the string buffer at byte position idx and
returns it.
Warning
This is an O(n) operation as it requires copying every element in the buffer.
Panics
If idx does not lie on a character boundary, or if it is out of
bounds, then this function will panic.
Examples
fn main() { let mut s = String::from("foo"); assert_eq!(s.remove(0), 'f'); assert_eq!(s.remove(1), 'o'); assert_eq!(s.remove(0), 'o'); }let mut s = String::from("foo"); assert_eq!(s.remove(0), 'f'); assert_eq!(s.remove(1), 'o'); assert_eq!(s.remove(0), 'o');
fn insert(&mut self, idx: usize, ch: char)
Inserts a character into the string buffer at byte position idx.
Warning
This is an O(n) operation as it requires copying every element in the buffer.
Panics
If idx does not lie on a character boundary or is out of bounds, then
this function will panic.
unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8>
Views the string buffer as a mutable sequence of bytes.
This is unsafe because it does not check to ensure that the resulting string will be valid UTF-8.
Examples
fn main() { let mut s = String::from("hello"); unsafe { let vec = s.as_mut_vec(); assert!(vec == &[104, 101, 108, 108, 111]); vec.reverse(); } assert_eq!(s, "olleh"); }let mut s = String::from("hello"); unsafe { let vec = s.as_mut_vec(); assert!(vec == &[104, 101, 108, 108, 111]); vec.reverse(); } assert_eq!(s, "olleh");
fn len(&self) -> usize
Returns the number of bytes in this string.
Examples
fn main() { let a = "foo".to_string(); assert_eq!(a.len(), 3); }let a = "foo".to_string(); assert_eq!(a.len(), 3);
fn is_empty(&self) -> bool
Returns true if the string contains no bytes
Examples
fn main() { let mut v = String::new(); assert!(v.is_empty()); v.push('a'); assert!(!v.is_empty()); }let mut v = String::new(); assert!(v.is_empty()); v.push('a'); assert!(!v.is_empty());
fn clear(&mut self)
Truncates the string, returning it to 0 length.
Examples
fn main() { let mut s = "foo".to_string(); s.clear(); assert!(s.is_empty()); }let mut s = "foo".to_string(); s.clear(); assert!(s.is_empty());
fn drain<R>(&mut self, range: R) -> Drain where R: RangeArgument<usize>
Create a draining iterator that removes the specified range in the string and yields the removed chars from start to end. The element range is removed even if the iterator is not consumed until the end.
Panics
Panics if the starting point or end point are not on character boundaries, or if they are out of bounds.
Examples
#![feature(drain)] fn main() { let mut s = String::from("α is alpha, β is beta"); let beta_offset = s.find('β').unwrap_or(s.len()); // Remove the range up until the β from the string let t: String = s.drain(..beta_offset).collect(); assert_eq!(t, "α is alpha, "); assert_eq!(s, "β is beta"); // A full range clears the string s.drain(..); assert_eq!(s, ""); }#![feature(drain)] let mut s = String::from("α is alpha, β is beta"); let beta_offset = s.find('β').unwrap_or(s.len()); // Remove the range up until the β from the string let t: String = s.drain(..beta_offset).collect(); assert_eq!(t, "α is alpha, "); assert_eq!(s, "β is beta"); // A full range clears the string s.drain(..); assert_eq!(s, "");
fn into_boxed_str(self) -> Box<str>
Converts the string into Box<str>.
Note that this will drop any excess capacity.
fn into_boxed_slice(self) -> Box<str>
: renamed to into_boxed_str
Converts the string into Box<str>.
Note that this will drop any excess capacity.
Methods from Deref<Target=str>
fn len(&self) -> usize
Returns the length of self in bytes.
Examples
fn main() { assert_eq!("foo".len(), 3); assert_eq!("ƒoo".len(), 4); // fancy f! }assert_eq!("foo".len(), 3); assert_eq!("ƒoo".len(), 4); // fancy f!
fn is_empty(&self) -> bool
Returns true if this slice has a length of zero bytes.
Examples
fn main() { assert!("".is_empty()); }assert!("".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 self to a byte slice.
Examples
fn main() { assert_eq!("bors".as_bytes(), b"bors"); }assert_eq!("bors".as_bytes(), b"bors");
fn as_ptr(&self) -> *const u8
Returns a raw pointer to the &str's buffer.
The caller must ensure that the string outlives this pointer, and that it is not reallocated (e.g. by pushing to the string).
Examples
fn main() { let s = "Hello"; let p = s.as_ptr(); }let s = "Hello"; let p = s.as_ptr();
unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str
Takes a bytewise slice from a string.
Returns the substring from [begin..end).
Safety
Caller must check both UTF-8 sequence boundaries and the boundaries of the entire slice as well.
Examples
fn main() { let s = "Löwe 老虎 Léopard"; unsafe { assert_eq!(s.slice_unchecked(0, 21), "Löwe 老虎 Léopard"); } }let s = "Löwe 老虎 Léopard"; unsafe { assert_eq!(s.slice_unchecked(0, 21), "Löwe 老虎 Léopard"); }
unsafe fn slice_mut_unchecked(&mut self, begin: usize, end: usize) -> &mut str
Takes a bytewise mutable slice from a string.
Same as slice_unchecked, but works with &mut str instead of &str.
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, return the next code point and its index.
This can be used to iterate over the Unicode code points of a string.
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, core)] 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, return the previous char and its position.
This function can be used to iterate over a Unicode code points in reverse.
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, core)] 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, return 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, return 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 code point 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 index mid is a byte offset from the start of the string
that must be on a char boundary.
Return slices &self[..mid] and &self[mid..].
Panics
Panics if mid is beyond the last code point of the string,
or if it is not on a char boundary.
Examples
fn main() { let s = "Löwe 老虎 Léopard"; let first_space = s.find(' ').unwrap_or(s.len()); let (a, b) = s.split_at(first_space); assert_eq!(a, "Löwe"); assert_eq!(b, " 老虎 Léopard"); }let s = "Löwe 老虎 Léopard"; let first_space = s.find(' ').unwrap_or(s.len()); let (a, b) = s.split_at(first_space); assert_eq!(a, "Löwe"); assert_eq!(b, " 老虎 Léopard");
fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)
Divide one mutable string slice into two at an index.
fn chars(&self) -> Chars
An iterator over the code points of self.
In Unicode relationship between code points and characters is complex. A single character may be composed of multiple code points (e.g. diacritical marks added to a letter), and a single code point (e.g. Hangul syllable) may contain multiple characters.
For iteration over human-readable characters a grapheme cluster iterator may be more appropriate. See the unicode-segmentation crate.
Examples
fn main() { let v: Vec<char> = "ASCII żółć 🇨🇭 한".chars().collect(); assert_eq!(v, ['A', 'S', 'C', 'I', 'I', ' ', 'z', '\u{307}', 'o', '\u{301}', 'ł', 'c', '\u{301}', ' ', '\u{1f1e8}', '\u{1f1ed}', ' ', '한']); }let v: Vec<char> = "ASCII żółć 🇨🇭 한".chars().collect(); assert_eq!(v, ['A', 'S', 'C', 'I', 'I', ' ', 'z', '\u{307}', 'o', '\u{301}', 'ł', 'c', '\u{301}', ' ', '\u{1f1e8}', '\u{1f1ed}', ' ', '한']);
fn char_indices(&self) -> CharIndices
An iterator over the chars of self and their byte offsets.
Examples
fn main() { let v: Vec<(usize, char)> = "A🇨🇭".char_indices().collect(); let b = vec![(0, 'A'), (1, '\u{1f1e8}'), (5, '\u{1f1ed}')]; assert_eq!(v, b); }let v: Vec<(usize, char)> = "A🇨🇭".char_indices().collect(); let b = vec![(0, 'A'), (1, '\u{1f1e8}'), (5, '\u{1f1ed}')]; assert_eq!(v, b);
fn bytes(&self) -> Bytes
An iterator over the bytes of self.
Examples
fn main() { let v: Vec<u8> = "bors".bytes().collect(); assert_eq!(v, b"bors".to_vec()); }let v: Vec<u8> = "bors".bytes().collect(); assert_eq!(v, b"bors".to_vec());
fn split_whitespace(&self) -> SplitWhitespace
An iterator over the non-empty substrings of self which contain no whitespace,
and which are separated by any amount of whitespace.
Examples
fn main() { let some_words = " Mary had\ta\u{2009}little \n\t lamb"; let v: Vec<&str> = some_words.split_whitespace().collect(); assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]); }let some_words = " Mary had\ta\u{2009}little \n\t lamb"; let v: Vec<&str> = some_words.split_whitespace().collect(); assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);
fn lines(&self) -> Lines
An iterator over the lines of a string, separated by \n or \r\n.
This does not include the empty string after a trailing newline or CRLF.
Examples
fn main() { let four_lines = "foo\nbar\n\r\nbaz"; let v: Vec<&str> = four_lines.lines().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]); }let four_lines = "foo\nbar\n\r\nbaz"; let v: Vec<&str> = four_lines.lines().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]);
Leaving off the trailing character:
fn main() { let four_lines = "foo\r\nbar\n\nbaz\n"; let v: Vec<&str> = four_lines.lines().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]); }let four_lines = "foo\r\nbar\n\nbaz\n"; let v: Vec<&str> = four_lines.lines().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]);
fn lines_any(&self) -> LinesAny
: use lines() instead now
An iterator over the lines of a string, separated by either
\n or \r\n.
As with .lines(), this does not include an empty trailing line.
Examples
fn main() { let four_lines = "foo\r\nbar\n\r\nbaz"; let v: Vec<&str> = four_lines.lines_any().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]); }let four_lines = "foo\r\nbar\n\r\nbaz"; let v: Vec<&str> = four_lines.lines_any().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]);
Leaving off the trailing character:
fn main() { let four_lines = "foo\r\nbar\n\r\nbaz\n"; let v: Vec<&str> = four_lines.lines_any().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]); }let four_lines = "foo\r\nbar\n\r\nbaz\n"; let v: Vec<&str> = four_lines.lines_any().collect(); assert_eq!(v, ["foo", "bar", "", "baz"]);
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 self contains another &str.
Examples
fn main() { assert!("bananas".contains("nana")); assert!(!"bananas".contains("foobar")); }assert!("bananas".contains("nana")); assert!(!"bananas".contains("foobar"));
fn starts_with<'a, P>(&'a self, pat: P) -> bool where P: Pattern<'a>
Returns true if the given &str is a prefix of the string.
Examples
fn main() { assert!("banana".starts_with("ba")); }assert!("banana".starts_with("ba"));
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 the string.
Examples
fn main() { assert!("banana".ends_with("nana")); }assert!("banana".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 self that matches
the pattern, if it
exists.
Returns None if it doesn't exist.
The pattern can be a simple &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 self that
matches the pattern, if it
exists.
Returns None if it doesn't exist.
The pattern can be a simple &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 self, separated by characters
matched by a pattern.
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.
Iterator behavior
The returned iterator will be double ended 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, rsplit() 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 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.
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, split() 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 self, separated by characters
matched by a pattern.
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 will be double ended 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, rsplit_terminator() can be used.
Examples
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, split_terminator() 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 self, separated by a pattern,
restricted to returning
at most count items.
The last element returned, if any, will contain the remainder of the
string.
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.
Iterator behavior
The returned iterator will not be double ended, because it is not efficient to support.
If the pattern allows a reverse search, rsplitn() 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 self, 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.
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.
Iterator behavior
The returned iterator will not be double ended, because it is not efficient to support.
splitn() can be used for splitting from the front.
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 self.
The pattern can be a simple &str, char, or a closure that
determines if a character matches.
Additional libraries might provide more complex patterns like
regular expressions.
Iterator behavior
The returned iterator will be double ended 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, rmatches() can be used.
Examples
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 self, yielded in
reverse order.
The pattern can be a simple &str, char, or a closure that
determines if a character matches.
Additional libraries might provide more complex patterns like
regular expressions.
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, matches() can be used.
Examples
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 self 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 simple &str, char, or a closure that determines
if a character matches. Additional libraries might provide more complex
patterns like regular expressions.
Iterator behavior
The returned iterator will be double ended 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, rmatch_indices() can be used.
Examples
#![feature(str_match_indices)] 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` }#![feature(str_match_indices)] 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 simple &str, char, or a closure that determines
if a character matches. Additional libraries might provide more complex
patterns like regular expressions.
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, match_indices() can be used.
Examples
#![feature(str_match_indices)] 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` }#![feature(str_match_indices)] 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 &str with leading and trailing whitespace removed.
Examples
fn main() { let s = " Hello\tworld\t"; assert_eq!(s.trim(), "Hello\tworld"); }let s = " Hello\tworld\t"; assert_eq!(s.trim(), "Hello\tworld");
fn trim_left(&self) -> &str
Returns a &str with leading whitespace removed.
Examples
fn main() { let s = " Hello\tworld\t"; assert_eq!(s.trim_left(), "Hello\tworld\t"); }let s = " Hello\tworld\t"; assert_eq!(s.trim_left(), "Hello\tworld\t");
fn trim_right(&self) -> &str
Returns a &str with trailing whitespace removed.
Examples
fn main() { let s = " Hello\tworld\t"; assert_eq!(s.trim_right(), " Hello\tworld"); }let s = " Hello\tworld\t"; assert_eq!(s.trim_right(), " Hello\tworld");
fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str where P: Pattern<'a>, P::Searcher: DoubleEndedSearcher<'a>
Returns a string with all pre- and suffixes that match a pattern repeatedly removed.
The pattern can be a simple 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 with all prefixes that match a pattern repeatedly removed.
The pattern can be a simple &str, char, or a closure that
determines if a character matches.
Examples
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 with all suffixes that match a pattern repeatedly removed.
The pattern can be a simple &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 self into the specified type.
Failure
Will return Err if it's not possible to parse self into the type.
Example
fn main() { assert_eq!("4".parse::<u32>(), Ok(4)); }assert_eq!("4".parse::<u32>(), Ok(4));
Failing:
fn main() { assert!("j".parse::<u32>().is_err()); }assert!("j".parse::<u32>().is_err());
fn replace(&self, from: &str, to: &str) -> String
Replaces all occurrences of one string with another.
replace takes two arguments, a sub-&str to find in self, and a
second &str to
replace it with. If the original &str isn't found, no change occurs.
Examples
fn main() { let s = "this is old"; assert_eq!(s.replace("old", "new"), "this is new"); }let s = "this is old"; assert_eq!(s.replace("old", "new"), "this is new");
When a &str isn't found:
let s = "this is old"; assert_eq!(s.replace("cookie monster", "little lamb"), s);
fn to_lowercase(&self) -> String
Returns the lowercase equivalent of this string.
Examples
fn main() { let s = "HELLO"; assert_eq!(s.to_lowercase(), "hello"); }let s = "HELLO"; assert_eq!(s.to_lowercase(), "hello");
fn to_uppercase(&self) -> String
Returns the uppercase equivalent of this string.
Examples
fn main() { let s = "hello"; assert_eq!(s.to_uppercase(), "HELLO"); }let s = "hello"; assert_eq!(s.to_uppercase(), "HELLO");
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 the Box<str> into a String without copying or allocating.
Trait Implementations
impl Borrow<str> for String
impl Clone for String
fn clone(&self) -> String
fn clone_from(&mut self, source: &String)
impl FromIterator<char> for String
fn from_iter<I>(iterable: I) -> String where I: IntoIterator<Item=char>
impl<'a> FromIterator<&'a str> for String
fn from_iter<I>(iterable: I) -> String where I: IntoIterator<Item=&'a str>
impl FromIterator<String> for String
fn from_iter<I>(iterable: I) -> String where I: IntoIterator<Item=String>
impl Extend<char> for String
fn extend<I>(&mut self, iterable: I) where I: IntoIterator<Item=char>
impl<'a> Extend<&'a char> for String
fn extend<I>(&mut self, iterable: I) where I: IntoIterator<Item=&'a char>
impl<'a> Extend<&'a str> for String
fn extend<I>(&mut self, iterable: I) where I: IntoIterator<Item=&'a str>
impl Extend<String> for String
fn extend<I>(&mut self, iterable: I) where I: IntoIterator<Item=String>
impl<'a, 'b> Pattern<'a> for &'b String
A convenience impl that delegates to the impl for &str