pub struct Text(pub String);
Expand description
The top-level UI text component.
Adding Text
to an entity will pull in required components for setting up a UI text node.
The string in this component is the first ‘text span’ in a hierarchy of text spans that are collected into
a ComputedTextBlock
. See TextSpan
for the component used by children of entities with Text
.
Note that Transform
on this entity is managed automatically by the UI layout system.
// Basic usage.
world.spawn(Text::new("hello world!"));
// With non-default style.
world.spawn((
Text::new("hello world!"),
TextFont {
font: font_handle.clone().into(),
font_size: 60.0,
..Default::default()
},
TextColor(BLUE.into()),
));
// With text justification.
world.spawn((
Text::new("hello world\nand bevy!"),
TextLayout::new_with_justify(JustifyText::Center)
));
Tuple Fields§
§0: String
Implementations§
Methods from Deref<Target = String>§
1.7.0 · Sourcepub fn as_str(&self) -> &str
pub fn as_str(&self) -> &str
Extracts a string slice containing the entire String
.
§Examples
let s = String::from("foo");
assert_eq!("foo", s.as_str());
1.7.0 · Sourcepub fn as_mut_str(&mut self) -> &mut str
pub fn as_mut_str(&mut self) -> &mut str
Converts a String
into a mutable string slice.
§Examples
let mut s = String::from("foobar");
let s_mut_str = s.as_mut_str();
s_mut_str.make_ascii_uppercase();
assert_eq!("FOOBAR", s_mut_str);
1.0.0 · Sourcepub fn push_str(&mut self, string: &str)
Available on non-no_global_oom_handling
only.
pub fn push_str(&mut self, string: &str)
no_global_oom_handling
only.Appends a given string slice onto the end of this String
.
§Examples
let mut s = String::from("foo");
s.push_str("bar");
assert_eq!("foobar", s);
Sourcepub fn extend_from_within<R>(&mut self, src: R)where
R: RangeBounds<usize>,
🔬This is a nightly-only experimental API. (string_extend_from_within
)Available on non-no_global_oom_handling
only.
pub fn extend_from_within<R>(&mut self, src: R)where
R: RangeBounds<usize>,
string_extend_from_within
)no_global_oom_handling
only.Copies elements from src
range to the end of the string.
§Panics
Panics if the starting point or end point do not lie on a char
boundary, or if they’re out of bounds.
§Examples
#![feature(string_extend_from_within)]
let mut string = String::from("abcde");
string.extend_from_within(2..);
assert_eq!(string, "abcdecde");
string.extend_from_within(..2);
assert_eq!(string, "abcdecdeab");
string.extend_from_within(4..8);
assert_eq!(string, "abcdecdeabecde");
1.0.0 · Sourcepub fn capacity(&self) -> usize
pub fn capacity(&self) -> usize
Returns this String
’s capacity, in bytes.
§Examples
let s = String::with_capacity(10);
assert!(s.capacity() >= 10);
1.0.0 · Sourcepub fn reserve(&mut self, additional: usize)
Available on non-no_global_oom_handling
only.
pub fn reserve(&mut self, additional: usize)
no_global_oom_handling
only.Reserves capacity for at least additional
bytes more than the
current length. The allocator may reserve more space to speculatively
avoid frequent allocations. After calling reserve
,
capacity will be greater than or equal to self.len() + additional
.
Does nothing if capacity is already sufficient.
§Panics
Panics if the new capacity overflows usize
.
§Examples
Basic usage:
let mut s = String::new();
s.reserve(10);
assert!(s.capacity() >= 10);
This might not actually increase the capacity:
let mut s = String::with_capacity(10);
s.push('a');
s.push('b');
// s now has a length of 2 and a capacity of at least 10
let capacity = s.capacity();
assert_eq!(2, s.len());
assert!(capacity >= 10);
// Since we already have at least an extra 8 capacity, calling this...
s.reserve(8);
// ... doesn't actually increase.
assert_eq!(capacity, s.capacity());
1.0.0 · Sourcepub fn reserve_exact(&mut self, additional: usize)
Available on non-no_global_oom_handling
only.
pub fn reserve_exact(&mut self, additional: usize)
no_global_oom_handling
only.Reserves the minimum capacity for at least additional
bytes more than
the current length. Unlike reserve
, this will not
deliberately over-allocate to speculatively avoid frequent allocations.
After calling reserve_exact
, capacity will be greater than or equal to
self.len() + additional
. Does nothing if the capacity is already
sufficient.
§Panics
Panics if the new capacity overflows usize
.
§Examples
Basic usage:
let mut s = String::new();
s.reserve_exact(10);
assert!(s.capacity() >= 10);
This might not actually increase the capacity:
let mut s = String::with_capacity(10);
s.push('a');
s.push('b');
// s now has a length of 2 and a capacity of at least 10
let capacity = s.capacity();
assert_eq!(2, s.len());
assert!(capacity >= 10);
// Since we already have at least an extra 8 capacity, calling this...
s.reserve_exact(8);
// ... doesn't actually increase.
assert_eq!(capacity, s.capacity());
1.57.0 · Sourcepub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>
pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>
Tries to reserve capacity for at least additional
bytes more than the
current length. The allocator may reserve more space to speculatively
avoid frequent allocations. After calling try_reserve
, capacity will be
greater than or equal to self.len() + additional
if it returns
Ok(())
. Does nothing if capacity is already sufficient. This method
preserves the contents even if an error occurs.
§Errors
If the capacity overflows, or the allocator reports a failure, then an error is returned.
§Examples
use std::collections::TryReserveError;
fn process_data(data: &str) -> Result<String, TryReserveError> {
let mut output = String::new();
// Pre-reserve the memory, exiting if we can't
output.try_reserve(data.len())?;
// Now we know this can't OOM in the middle of our complex work
output.push_str(data);
Ok(output)
}
1.57.0 · Sourcepub fn try_reserve_exact(
&mut self,
additional: usize,
) -> Result<(), TryReserveError>
pub fn try_reserve_exact( &mut self, additional: usize, ) -> Result<(), TryReserveError>
Tries to reserve the minimum capacity for at least additional
bytes
more than the current length. Unlike try_reserve
, this will not
deliberately over-allocate to speculatively avoid frequent allocations.
After calling try_reserve_exact
, capacity will be greater than or
equal to self.len() + additional
if it returns Ok(())
.
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 try_reserve
if future insertions are expected.
§Errors
If the capacity overflows, or the allocator reports a failure, then an error is returned.
§Examples
use std::collections::TryReserveError;
fn process_data(data: &str) -> Result<String, TryReserveError> {
let mut output = String::new();
// Pre-reserve the memory, exiting if we can't
output.try_reserve_exact(data.len())?;
// Now we know this can't OOM in the middle of our complex work
output.push_str(data);
Ok(output)
}
1.0.0 · Sourcepub fn shrink_to_fit(&mut self)
Available on non-no_global_oom_handling
only.
pub fn shrink_to_fit(&mut self)
no_global_oom_handling
only.Shrinks the capacity of this String
to match its length.
§Examples
let mut s = String::from("foo");
s.reserve(100);
assert!(s.capacity() >= 100);
s.shrink_to_fit();
assert_eq!(3, s.capacity());
1.56.0 · Sourcepub fn shrink_to(&mut self, min_capacity: usize)
Available on non-no_global_oom_handling
only.
pub fn shrink_to(&mut self, min_capacity: usize)
no_global_oom_handling
only.Shrinks the capacity of this String
with a lower bound.
The capacity will remain at least as large as both the length and the supplied value.
If the current capacity is less than the lower limit, this is a no-op.
§Examples
let mut s = String::from("foo");
s.reserve(100);
assert!(s.capacity() >= 100);
s.shrink_to(10);
assert!(s.capacity() >= 10);
s.shrink_to(0);
assert!(s.capacity() >= 3);
1.0.0 · Sourcepub fn truncate(&mut self, new_len: usize)
pub fn truncate(&mut self, new_len: usize)
Shortens this String
to the specified length.
If new_len
is greater than or equal to the string’s current length, this has no
effect.
Note that this method has no effect on the allocated capacity of the string
§Panics
Panics if new_len
does not lie on a char
boundary.
§Examples
let mut s = String::from("hello");
s.truncate(2);
assert_eq!("he", s);
1.0.0 · Sourcepub fn remove(&mut self, idx: usize) -> char
pub fn remove(&mut self, idx: usize) -> char
Removes a char
from this String
at a byte position and returns it.
This is an O(n) operation, as it requires copying every element in the buffer.
§Panics
Panics if idx
is larger than or equal to the String
’s length,
or if it does not lie on a char
boundary.
§Examples
let mut s = String::from("abç");
assert_eq!(s.remove(0), 'a');
assert_eq!(s.remove(1), 'ç');
assert_eq!(s.remove(0), 'b');
Sourcepub fn remove_matches<P>(&mut self, pat: P)where
P: Pattern,
🔬This is a nightly-only experimental API. (string_remove_matches
)Available on non-no_global_oom_handling
only.
pub fn remove_matches<P>(&mut self, pat: P)where
P: Pattern,
string_remove_matches
)no_global_oom_handling
only.Remove all matches of pattern pat
in the String
.
§Examples
#![feature(string_remove_matches)]
let mut s = String::from("Trees are not green, the sky is not blue.");
s.remove_matches("not ");
assert_eq!("Trees are green, the sky is blue.", s);
Matches will be detected and removed iteratively, so in cases where patterns overlap, only the first pattern will be removed:
#![feature(string_remove_matches)]
let mut s = String::from("banana");
s.remove_matches("ana");
assert_eq!("bna", s);
1.26.0 · Sourcepub fn retain<F>(&mut self, f: F)
pub fn retain<F>(&mut self, f: F)
Retains only the characters specified by the predicate.
In other words, remove all characters c
such that f(c)
returns false
.
This method operates in place, visiting each character exactly once in the
original order, and preserves the order of the retained characters.
§Examples
let mut s = String::from("f_o_ob_ar");
s.retain(|c| c != '_');
assert_eq!(s, "foobar");
Because the elements are visited exactly once in the original order, external state may be used to decide which elements to keep.
let mut s = String::from("abcde");
let keep = [false, true, true, false, true];
let mut iter = keep.iter();
s.retain(|_| *iter.next().unwrap());
assert_eq!(s, "bce");
1.0.0 · Sourcepub fn insert(&mut self, idx: usize, ch: char)
Available on non-no_global_oom_handling
only.
pub fn insert(&mut self, idx: usize, ch: char)
no_global_oom_handling
only.Inserts a character into this String
at a byte position.
This is an O(n) operation as it requires copying every element in the buffer.
§Panics
Panics if idx
is larger than the String
’s length, or if it does not
lie on a char
boundary.
§Examples
let mut s = String::with_capacity(3);
s.insert(0, 'f');
s.insert(1, 'o');
s.insert(2, 'o');
assert_eq!("foo", s);
1.16.0 · Sourcepub fn insert_str(&mut self, idx: usize, string: &str)
Available on non-no_global_oom_handling
only.
pub fn insert_str(&mut self, idx: usize, string: &str)
no_global_oom_handling
only.Inserts a string slice into this String
at a byte position.
This is an O(n) operation as it requires copying every element in the buffer.
§Panics
Panics if idx
is larger than the String
’s length, or if it does not
lie on a char
boundary.
§Examples
let mut s = String::from("bar");
s.insert_str(0, "foo");
assert_eq!("foobar", s);
1.0.0 · Sourcepub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8> ⓘ
pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8> ⓘ
Returns a mutable reference to the contents of this String
.
§Safety
This function is unsafe because the returned &mut Vec
allows writing
bytes which are not valid UTF-8. If this constraint is violated, using
the original String
after dropping the &mut Vec
may violate memory
safety, as the rest of the standard library assumes that String
s are
valid UTF-8.
§Examples
let mut s = String::from("hello");
unsafe {
let vec = s.as_mut_vec();
assert_eq!(&[104, 101, 108, 108, 111][..], &vec[..]);
vec.reverse();
}
assert_eq!(s, "olleh");
1.0.0 · Sourcepub fn len(&self) -> usize
pub fn len(&self) -> usize
Returns the length of this String
, in bytes, not char
s or
graphemes. In other words, it might not be what a human considers the
length of the string.
§Examples
let a = String::from("foo");
assert_eq!(a.len(), 3);
let fancy_f = String::from("ƒoo");
assert_eq!(fancy_f.len(), 4);
assert_eq!(fancy_f.chars().count(), 3);
1.0.0 · Sourcepub fn is_empty(&self) -> bool
pub fn is_empty(&self) -> bool
Returns true
if this String
has a length of zero, and false
otherwise.
§Examples
let mut v = String::new();
assert!(v.is_empty());
v.push('a');
assert!(!v.is_empty());
1.16.0 · Sourcepub fn split_off(&mut self, at: usize) -> String
Available on non-no_global_oom_handling
only.
pub fn split_off(&mut self, at: usize) -> String
no_global_oom_handling
only.Splits the string into two at the given byte index.
Returns a newly allocated String
. self
contains bytes [0, at)
, and
the returned String
contains bytes [at, len)
. at
must be on the
boundary of a UTF-8 code point.
Note that the capacity of self
does not change.
§Panics
Panics if at
is not on a UTF-8
code point boundary, or if it is beyond the last
code point of the string.
§Examples
let mut hello = String::from("Hello, World!");
let world = hello.split_off(7);
assert_eq!(hello, "Hello, ");
assert_eq!(world, "World!");
1.0.0 · Sourcepub fn clear(&mut self)
pub fn clear(&mut self)
Truncates this String
, removing all contents.
While this means the String
will have a length of zero, it does not
touch its capacity.
§Examples
let mut s = String::from("foo");
s.clear();
assert!(s.is_empty());
assert_eq!(0, s.len());
assert_eq!(3, s.capacity());
1.6.0 · Sourcepub fn drain<R>(&mut self, range: R) -> Drain<'_>where
R: RangeBounds<usize>,
pub fn drain<R>(&mut self, range: R) -> Drain<'_>where
R: RangeBounds<usize>,
Removes the specified range from the string in bulk, returning all removed characters as an iterator.
The returned iterator keeps a mutable borrow on the string to optimize its implementation.
§Panics
Panics if the starting point or end point do not lie on a char
boundary, or if they’re out of bounds.
§Leaking
If the returned iterator goes out of scope without being dropped (due to
core::mem::forget
, for example), the string may still contain a copy
of any drained characters, or may have lost characters arbitrarily,
including characters outside the range.
§Examples
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, like `clear()` does
s.drain(..);
assert_eq!(s, "");
1.27.0 · Sourcepub fn replace_range<R>(&mut self, range: R, replace_with: &str)where
R: RangeBounds<usize>,
Available on non-no_global_oom_handling
only.
pub fn replace_range<R>(&mut self, range: R, replace_with: &str)where
R: RangeBounds<usize>,
no_global_oom_handling
only.Removes the specified range in the string, and replaces it with the given string. The given string doesn’t need to be the same length as the range.
§Panics
Panics if the starting point or end point do not lie on a char
boundary, or if they’re out of bounds.
§Examples
let mut s = String::from("α is alpha, β is beta");
let beta_offset = s.find('β').unwrap_or(s.len());
// Replace the range up until the β from the string
s.replace_range(..beta_offset, "Α is capital alpha; ");
assert_eq!(s, "Α is capital alpha; β is beta");
Methods from Deref<Target = str>§
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
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
.
If index
is greater than the length of the string, this returns the length of the string.
This method is the natural complement to floor_char_boundary
. See that method
for more details.
§Examples
#![feature(round_char_boundary)]
let s = "❤️🧡💛💚💙💜";
assert_eq!(s.len(), 26);
assert!(!s.is_char_boundary(13));
let closest = s.ceil_char_boundary(13);
assert_eq!(closest, 14);
assert_eq!(&s[..closest], "❤️🧡💛");
1.20.0 · Sourcepub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] ⓘ
pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] ⓘ
Converts a mutable string slice to a mutable byte slice.
§Safety
The caller must ensure that the content of the slice is valid UTF-8
before the borrow ends and the underlying str
is used.
Use of a str
whose contents are not valid UTF-8 is undefined behavior.
§Examples
Basic usage:
let mut s = String::from("Hello");
let bytes = unsafe { s.as_bytes_mut() };
assert_eq!(b"Hello", bytes);
Mutability:
let mut s = String::from("🗻∈🌏");
unsafe {
let bytes = s.as_bytes_mut();
bytes[0] = 0xF0;
bytes[1] = 0x9F;
bytes[2] = 0x8D;
bytes[3] = 0x94;
}
assert_eq!("🍔∈🌏", s);
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
let s = "Hello";
let ptr = s.as_ptr();
1.36.0 · Sourcepub fn as_mut_ptr(&mut self) -> *mut u8
pub fn as_mut_ptr(&mut self) -> *mut u8
Converts a mutable string slice to a raw pointer.
As string slices are a slice of bytes, the raw pointer points to a
u8
. This pointer will be pointing to the first byte of the string
slice.
It is your responsibility to make sure that the string slice only gets modified in a way that it remains valid UTF-8.
1.20.0 · Sourcepub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
pub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
Returns a subslice of str
.
This is the non-panicking alternative to indexing the str
. Returns
None
whenever equivalent indexing operation would panic.
§Examples
let v = String::from("🗻∈🌏");
assert_eq!(Some("🗻"), v.get(0..4));
// indices not on UTF-8 sequence boundaries
assert!(v.get(1..).is_none());
assert!(v.get(..8).is_none());
// out of bounds
assert!(v.get(..42).is_none());
1.20.0 · Sourcepub fn get_mut<I>(
&mut self,
i: I,
) -> Option<&mut <I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
pub fn get_mut<I>(
&mut self,
i: I,
) -> Option<&mut <I as SliceIndex<str>>::Output>where
I: SliceIndex<str>,
Returns a mutable subslice of str
.
This is the non-panicking alternative to indexing the str
. Returns
None
whenever equivalent indexing operation would panic.
§Examples
let mut v = String::from("hello");
// correct length
assert!(v.get_mut(0..5).is_some());
// out of bounds
assert!(v.get_mut(..42).is_none());
assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));
assert_eq!("hello", v);
{
let s = v.get_mut(0..2);
let s = s.map(|s| {
s.make_ascii_uppercase();
&*s
});
assert_eq!(Some("HE"), s);
}
assert_eq!("HEllo", v);
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));
}
1.20.0 · Sourcepub unsafe fn get_unchecked_mut<I>(
&mut self,
i: I,
) -> &mut <I as SliceIndex<str>>::Outputwhere
I: SliceIndex<str>,
pub unsafe fn get_unchecked_mut<I>(
&mut self,
i: I,
) -> &mut <I as SliceIndex<str>>::Outputwhere
I: SliceIndex<str>,
Returns a mutable, unchecked subslice of str
.
This is the unchecked alternative to indexing the str
.
§Safety
Callers of this function are responsible that these preconditions are satisfied:
- The starting index must not exceed the ending index;
- Indexes must be within bounds of the original slice;
- Indexes must lie on UTF-8 sequence boundaries.
Failing that, the returned string slice may reference invalid memory or
violate the invariants communicated by the str
type.
§Examples
let mut v = String::from("🗻∈🌏");
unsafe {
assert_eq!("🗻", v.get_unchecked_mut(0..4));
assert_eq!("∈", v.get_unchecked_mut(4..7));
assert_eq!("🌏", v.get_unchecked_mut(7..11));
}
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:
begin
must not exceedend
.begin
andend
must be byte positions within the string slice.begin
andend
must lie on UTF-8 sequence boundaries.
§Examples
let s = "Löwe 老虎 Léopard";
unsafe {
assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21));
}
let s = "Hello, world!";
unsafe {
assert_eq!("world", s.slice_unchecked(7, 12));
}
1.5.0 · Sourcepub unsafe fn slice_mut_unchecked(
&mut self,
begin: usize,
end: usize,
) -> &mut str
👎Deprecated since 1.29.0: use get_unchecked_mut(begin..end)
instead
pub unsafe fn slice_mut_unchecked( &mut self, begin: usize, end: usize, ) -> &mut str
get_unchecked_mut(begin..end)
insteadCreates a string slice from another string slice, bypassing safety checks.
This is generally not recommended, use with caution! For a safe
alternative see str
and IndexMut
.
This new slice goes from begin
to end
, including begin
but
excluding end
.
To get an immutable string slice instead, see the
slice_unchecked
method.
§Safety
Callers of this function are responsible that three preconditions are satisfied:
begin
must not exceedend
.begin
andend
must be byte positions within the string slice.begin
andend
must lie on UTF-8 sequence boundaries.
1.4.0 · Sourcepub fn split_at(&self, mid: usize) -> (&str, &str)
pub fn split_at(&self, mid: usize) -> (&str, &str)
Divides one string slice into two at an index.
The argument, mid
, should be a byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get mutable string slices instead, see the split_at_mut
method.
§Panics
Panics if mid
is not on a UTF-8 code point boundary, or if it is past
the end of the last code point of the string slice. For a non-panicking
alternative see split_at_checked
.
§Examples
let s = "Per Martin-Löf";
let (first, last) = s.split_at(3);
assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);
1.4.0 · Sourcepub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)
pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)
Divides one mutable string slice into two at an index.
The argument, mid
, should be a byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get immutable string slices instead, see the split_at
method.
§Panics
Panics if mid
is not on a UTF-8 code point boundary, or if it is past
the end of the last code point of the string slice. For a non-panicking
alternative see split_at_mut_checked
.
§Examples
let mut s = "Per Martin-Löf".to_string();
{
let (first, last) = s.split_at_mut(3);
first.make_ascii_uppercase();
assert_eq!("PER", first);
assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);
1.80.0 · Sourcepub fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)>
pub fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)>
Divides one string slice into two at an index.
The argument, mid
, should be a valid byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point. The
method returns None
if that’s not the case.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get mutable string slices instead, see the split_at_mut_checked
method.
§Examples
let s = "Per Martin-Löf";
let (first, last) = s.split_at_checked(3).unwrap();
assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);
assert_eq!(None, s.split_at_checked(13)); // Inside “ö”
assert_eq!(None, s.split_at_checked(16)); // Beyond the string length
1.80.0 · Sourcepub fn split_at_mut_checked(
&mut self,
mid: usize,
) -> Option<(&mut str, &mut str)>
pub fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut str, &mut str)>
Divides one mutable string slice into two at an index.
The argument, mid
, should be a valid byte offset from the start of the
string. It must also be on the boundary of a UTF-8 code point. The
method returns None
if that’s not the case.
The two slices returned go from the start of the string slice to mid
,
and from mid
to the end of the string slice.
To get immutable string slices instead, see the split_at_checked
method.
§Examples
let mut s = "Per Martin-Löf".to_string();
if let Some((first, last)) = s.split_at_mut_checked(3) {
first.make_ascii_uppercase();
assert_eq!("PER", first);
assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);
assert_eq!(None, s.split_at_mut_checked(13)); // Inside “ö”
assert_eq!(None, s.split_at_mut_checked(16)); // Beyond the string length
1.0.0 · Sourcepub fn chars(&self) -> Chars<'_>
pub fn chars(&self) -> Chars<'_>
Returns an iterator over the char
s of a string slice.
As a string slice consists of valid UTF-8, we can iterate through a
string slice by char
. This method returns such an iterator.
It’s important to remember that char
represents a Unicode Scalar
Value, and might not match your idea of what a ‘character’ is. Iteration
over grapheme clusters may be what you actually want. This functionality
is not provided by Rust’s standard library, check crates.io instead.
§Examples
Basic usage:
let word = "goodbye";
let count = word.chars().count();
assert_eq!(7, count);
let mut chars = word.chars();
assert_eq!(Some('g'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('d'), chars.next());
assert_eq!(Some('b'), chars.next());
assert_eq!(Some('y'), chars.next());
assert_eq!(Some('e'), chars.next());
assert_eq!(None, chars.next());
Remember, char
s might not match your intuition about characters:
let y = "y̆";
let mut chars = y.chars();
assert_eq!(Some('y'), chars.next()); // not 'y̆'
assert_eq!(Some('\u{0306}'), chars.next());
assert_eq!(None, chars.next());
1.0.0 · Sourcepub fn char_indices(&self) -> CharIndices<'_>
pub fn char_indices(&self) -> CharIndices<'_>
Returns an iterator over the char
s of a string slice, and their
positions.
As a string slice consists of valid UTF-8, we can iterate through a
string slice by char
. This method returns an iterator of both
these char
s, as well as their byte positions.
The iterator yields tuples. The position is first, the char
is
second.
§Examples
Basic usage:
let word = "goodbye";
let count = word.char_indices().count();
assert_eq!(7, count);
let mut char_indices = word.char_indices();
assert_eq!(Some((0, 'g')), char_indices.next());
assert_eq!(Some((1, 'o')), char_indices.next());
assert_eq!(Some((2, 'o')), char_indices.next());
assert_eq!(Some((3, 'd')), char_indices.next());
assert_eq!(Some((4, 'b')), char_indices.next());
assert_eq!(Some((5, 'y')), char_indices.next());
assert_eq!(Some((6, 'e')), char_indices.next());
assert_eq!(None, char_indices.next());
Remember, char
s might not match your intuition about characters:
let yes = "y̆es";
let mut char_indices = yes.char_indices();
assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
assert_eq!(Some((1, '\u{0306}')), char_indices.next());
// note the 3 here - the previous character took up two bytes
assert_eq!(Some((3, 'e')), char_indices.next());
assert_eq!(Some((4, 's')), char_indices.next());
assert_eq!(None, char_indices.next());
1.0.0 · Sourcepub fn bytes(&self) -> Bytes<'_>
pub fn bytes(&self) -> Bytes<'_>
Returns an iterator over the bytes of a string slice.
As a string slice consists of a sequence of bytes, we can iterate through a string slice by byte. This method returns such an iterator.
§Examples
let mut bytes = "bors".bytes();
assert_eq!(Some(b'b'), bytes.next());
assert_eq!(Some(b'o'), bytes.next());
assert_eq!(Some(b'r'), bytes.next());
assert_eq!(Some(b's'), bytes.next());
assert_eq!(None, bytes.next());
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<'_>
Returns an iterator over the lines of a string, as string slices.
Lines are split at line endings that are either newlines (\n
) or
sequences of a carriage return followed by a line feed (\r\n
).
Line terminators are not included in the lines returned by the iterator.
Note that any carriage return (\r
) not immediately followed by a
line feed (\n
) does not split a line. These carriage returns are
thereby included in the produced lines.
The final line ending is optional. A string that ends with a final line ending will return the same lines as an otherwise identical string without a final line ending.
§Examples
Basic usage:
let text = "foo\r\nbar\n\nbaz\r";
let mut lines = text.lines();
assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
// Trailing carriage return is included in the last line
assert_eq!(Some("baz\r"), lines.next());
assert_eq!(None, lines.next());
The final line does not require any ending:
let text = "foo\nbar\n\r\nbaz";
let mut lines = text.lines();
assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
assert_eq!(Some("baz"), lines.next());
assert_eq!(None, lines.next());
1.0.0 · Sourcepub fn lines_any(&self) -> LinesAny<'_>
👎Deprecated since 1.4.0: use lines() instead now
pub fn lines_any(&self) -> LinesAny<'_>
Returns 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
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<P>(&self, pat: P) -> boolwhere
P: Pattern,
pub fn contains<P>(&self, pat: P) -> boolwhere
P: Pattern,
Returns true
if the given pattern matches a sub-slice of
this string slice.
Returns false
if it does not.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
let bananas = "bananas";
assert!(bananas.contains("nana"));
assert!(!bananas.contains("apples"));
1.0.0 · Sourcepub fn starts_with<P>(&self, pat: P) -> boolwhere
P: Pattern,
pub fn starts_with<P>(&self, pat: P) -> boolwhere
P: Pattern,
Returns true
if the given pattern matches a prefix of this
string slice.
Returns false
if it does not.
The pattern can be a &str
, in which case this function will return true if
the &str
is a prefix of this string slice.
The pattern can also be a char
, a slice of char
s, or a
function or closure that determines if a character matches.
These will only be checked against the first character of this string slice.
Look at the second example below regarding behavior for slices of char
s.
§Examples
let bananas = "bananas";
assert!(bananas.starts_with("bana"));
assert!(!bananas.starts_with("nana"));
let bananas = "bananas";
// Note that both of these assert successfully.
assert!(bananas.starts_with(&['b', 'a', 'n', 'a']));
assert!(bananas.starts_with(&['a', 'b', 'c', 'd']));
1.0.0 · Sourcepub fn ends_with<P>(&self, pat: P) -> bool
pub fn ends_with<P>(&self, pat: P) -> bool
Returns true
if the given pattern matches a suffix of this
string slice.
Returns false
if it does not.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
let bananas = "bananas";
assert!(bananas.ends_with("anas"));
assert!(!bananas.ends_with("nana"));
1.0.0 · Sourcepub fn find<P>(&self, pat: P) -> Option<usize>where
P: Pattern,
pub fn find<P>(&self, pat: P) -> Option<usize>where
P: Pattern,
Returns the byte index of the first character of this string slice that matches the pattern.
Returns None
if the pattern doesn’t match.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi";
assert_eq!(s.find('L'), Some(0));
assert_eq!(s.find('é'), Some(14));
assert_eq!(s.find("pard"), Some(17));
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<P>(&self, pat: P) -> Option<usize>
pub fn rfind<P>(&self, pat: P) -> Option<usize>
Returns the byte index for the first character of the last match of the pattern in this string slice.
Returns None
if the pattern doesn’t match.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi";
assert_eq!(s.rfind('L'), Some(13));
assert_eq!(s.rfind('é'), Some(14));
assert_eq!(s.rfind("pard"), Some(24));
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<P>(&self, pat: P) -> Split<'_, P>where
P: Pattern,
pub fn split<P>(&self, pat: P) -> Split<'_, P>where
P: Pattern,
Returns an iterator over substrings of this string slice, separated by characters matched by a pattern.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rsplit
method can be used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);
let v: Vec<&str> = "".split('X').collect();
assert_eq!(v, [""]);
let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
assert_eq!(v, ["lion", "", "tiger", "leopard"]);
let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);
let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect();
assert_eq!(v, ["abc", "def", "ghi"]);
let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);
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<P>(&self, pat: P) -> SplitInclusive<'_, P>where
P: Pattern,
pub fn split_inclusive<P>(&self, pat: P) -> SplitInclusive<'_, P>where
P: Pattern,
Returns an iterator over substrings of this string slice, separated by characters matched by a pattern.
Differs from the iterator produced by split
in that split_inclusive
leaves the matched part as the terminator of the substring.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
.split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);
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<P>(&self, pat: P) -> RSplit<'_, P>
pub fn rsplit<P>(&self, pat: P) -> RSplit<'_, P>
Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern and yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse
search, and it will be a DoubleEndedIterator
if a forward/reverse
search yields the same elements.
For iterating from the front, the split
method can be used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);
let v: Vec<&str> = "".rsplit('X').collect();
assert_eq!(v, [""]);
let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
assert_eq!(v, ["leopard", "tiger", "", "lion"]);
let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
assert_eq!(v, ["leopard", "tiger", "lion"]);
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<P>(&self, pat: P) -> SplitTerminator<'_, P>where
P: Pattern,
pub fn split_terminator<P>(&self, pat: P) -> SplitTerminator<'_, P>where
P: Pattern,
Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
Equivalent to split
, except that the trailing substring
is skipped if empty.
This method can be used for string data that is terminated, rather than separated by a pattern.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rsplit_terminator
method can be used.
§Examples
let v: Vec<&str> = "A.B.".split_terminator('.').collect();
assert_eq!(v, ["A", "B"]);
let v: Vec<&str> = "A..B..".split_terminator(".").collect();
assert_eq!(v, ["A", "", "B", ""]);
let v: Vec<&str> = "A.B:C.D".split_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["A", "B", "C", "D"]);
1.0.0 · Sourcepub fn rsplit_terminator<P>(&self, pat: P) -> RSplitTerminator<'_, P>
pub fn rsplit_terminator<P>(&self, pat: P) -> RSplitTerminator<'_, P>
Returns an iterator over substrings of self
, separated by characters
matched by a pattern and yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
Equivalent to split
, except that the trailing substring is
skipped if empty.
This method can be used for string data that is terminated, rather than separated by a pattern.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse search, and it will be double ended if a forward/reverse search yields the same elements.
For iterating from the front, the split_terminator
method can be
used.
§Examples
let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
assert_eq!(v, ["B", "A"]);
let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
assert_eq!(v, ["", "B", "", "A"]);
let v: Vec<&str> = "A.B:C.D".rsplit_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["D", "C", "B", "A"]);
1.0.0 · Sourcepub fn splitn<P>(&self, n: usize, pat: P) -> SplitN<'_, P>where
P: Pattern,
pub fn splitn<P>(&self, n: usize, pat: P) -> SplitN<'_, P>where
P: Pattern,
Returns an iterator over substrings of the given string slice, separated
by a pattern, restricted to returning at most n
items.
If n
substrings are returned, the last substring (the n
th substring)
will contain the remainder of the string.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will not be double ended, because it is not efficient to support.
If the pattern allows a reverse search, the rsplitn
method can be
used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
assert_eq!(v, ["Mary", "had", "a little lambda"]);
let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
assert_eq!(v, ["lion", "", "tigerXleopard"]);
let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
assert_eq!(v, ["abcXdef"]);
let v: Vec<&str> = "".splitn(1, 'X').collect();
assert_eq!(v, [""]);
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<P>(&self, n: usize, pat: P) -> RSplitN<'_, P>
pub fn rsplitn<P>(&self, n: usize, pat: P) -> RSplitN<'_, P>
Returns an iterator over substrings of this string slice, separated by a
pattern, starting from the end of the string, restricted to returning at
most n
items.
If n
substrings are returned, the last substring (the n
th substring)
will contain the remainder of the string.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will not be double ended, because it is not efficient to support.
For splitting from the front, the splitn
method can be used.
§Examples
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
assert_eq!(v, ["lamb", "little", "Mary had a"]);
let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
assert_eq!(v, ["leopard", "tiger", "lionX"]);
let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
assert_eq!(v, ["leopard", "lion::tiger"]);
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<P>(&self, delimiter: P) -> Option<(&str, &str)>where
P: Pattern,
pub fn split_once<P>(&self, delimiter: P) -> Option<(&str, &str)>where
P: Pattern,
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<P>(&self, delimiter: P) -> Option<(&str, &str)>
pub fn rsplit_once<P>(&self, delimiter: P) -> Option<(&str, &str)>
Splits the string on the last occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.
§Examples
assert_eq!("cfg".rsplit_once('='), None);
assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));
1.2.0 · Sourcepub fn matches<P>(&self, pat: P) -> Matches<'_, P>where
P: Pattern,
pub fn matches<P>(&self, pat: P) -> Matches<'_, P>where
P: Pattern,
Returns an iterator over the disjoint matches of a pattern within the given string slice.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rmatches
method can be used.
§Examples
let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);
let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect();
assert_eq!(v, ["1", "2", "3"]);
1.2.0 · Sourcepub fn rmatches<P>(&self, pat: P) -> RMatches<'_, P>
pub fn rmatches<P>(&self, pat: P) -> RMatches<'_, P>
Returns an iterator over the disjoint matches of a pattern within this string slice, yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse
search, and it will be a DoubleEndedIterator
if a forward/reverse
search yields the same elements.
For iterating from the front, the matches
method can be used.
§Examples
let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);
let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect();
assert_eq!(v, ["3", "2", "1"]);
1.5.0 · Sourcepub fn match_indices<P>(&self, pat: P) -> MatchIndices<'_, P>where
P: Pattern,
pub fn match_indices<P>(&self, pat: P) -> MatchIndices<'_, P>where
P: Pattern,
Returns an iterator over the disjoint matches of a pattern within this string slice as well as the index that the match starts at.
For matches of pat
within self
that overlap, only the indices
corresponding to the first match are returned.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator will be a DoubleEndedIterator
if the pattern
allows a reverse search and forward/reverse search yields the same
elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ
from a forward search, the rmatch_indices
method can be used.
§Examples
let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect();
assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]);
let v: Vec<_> = "1abcabc2".match_indices("abc").collect();
assert_eq!(v, [(1, "abc"), (4, "abc")]);
let v: Vec<_> = "ababa".match_indices("aba").collect();
assert_eq!(v, [(0, "aba")]); // only the first `aba`
1.5.0 · Sourcepub fn rmatch_indices<P>(&self, pat: P) -> RMatchIndices<'_, P>
pub fn rmatch_indices<P>(&self, pat: P) -> RMatchIndices<'_, P>
Returns an iterator over the disjoint matches of a pattern within self
,
yielded in reverse order along with the index of the match.
For matches of pat
within self
that overlap, only the indices
corresponding to the last match are returned.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Iterator behavior
The returned iterator requires that the pattern supports a reverse
search, and it will be a DoubleEndedIterator
if a forward/reverse
search yields the same elements.
For iterating from the front, the match_indices
method can be used.
§Examples
let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect();
assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]);
let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect();
assert_eq!(v, [(4, "abc"), (1, "abc")]);
let v: Vec<_> = "ababa".rmatch_indices("aba").collect();
assert_eq!(v, [(2, "aba")]); // only the last `aba`
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
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_start
Returns a string slice with leading whitespace removed.
‘Whitespace’ is defined according to the terms of the Unicode Derived
Core Property White_Space
.
§Text directionality
A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.
§Examples
Basic usage:
let s = " Hello\tworld\t";
assert_eq!("Hello\tworld\t", s.trim_left());
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_end
Returns a string slice with trailing whitespace removed.
‘Whitespace’ is defined according to the terms of the Unicode Derived
Core Property White_Space
.
§Text directionality
A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.
§Examples
Basic usage:
let s = " Hello\tworld\t";
assert_eq!(" Hello\tworld", s.trim_right());
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<P>(&self, pat: P) -> &str
pub fn trim_matches<P>(&self, pat: P) -> &str
Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.
The pattern can be a char
, a slice of char
s, or a function
or closure that determines if a character matches.
§Examples
Simple patterns:
assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");
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<P>(&self, pat: P) -> &strwhere
P: Pattern,
pub fn trim_start_matches<P>(&self, pat: P) -> &strwhere
P: Pattern,
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. start
in this context means the first
position of that byte string; for a left-to-right language like English or
Russian, this will be left side, and for right-to-left languages like
Arabic or Hebrew, this will be the right side.
§Examples
assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");
1.45.0 · Sourcepub fn strip_prefix<P>(&self, prefix: P) -> Option<&str>where
P: Pattern,
pub fn strip_prefix<P>(&self, prefix: P) -> Option<&str>where
P: Pattern,
Returns a string slice with the prefix removed.
If the string starts with the pattern prefix
, returns the substring after the prefix,
wrapped in Some
. Unlike trim_start_matches
, this method removes the prefix exactly once.
If the string does not start with prefix
, returns None
.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar"));
assert_eq!("foo:bar".strip_prefix("bar"), None);
assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));
1.45.0 · Sourcepub fn strip_suffix<P>(&self, suffix: P) -> Option<&str>
pub fn strip_suffix<P>(&self, suffix: P) -> Option<&str>
Returns a string slice with the suffix removed.
If the string ends with the pattern suffix
, returns the substring before the suffix,
wrapped in Some
. Unlike trim_end_matches
, this method removes the suffix exactly once.
If the string does not end with suffix
, returns None
.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Examples
assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar"));
assert_eq!("bar:foo".strip_suffix("bar"), None);
assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));
1.30.0 · Sourcepub fn trim_end_matches<P>(&self, pat: P) -> &str
pub fn trim_end_matches<P>(&self, pat: P) -> &str
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. end
in this context means the last
position of that byte string; for a left-to-right language like English or
Russian, this will be right side, and for right-to-left languages like
Arabic or Hebrew, this will be the left side.
§Examples
Simple patterns:
assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");
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<P>(&self, pat: P) -> &strwhere
P: Pattern,
👎Deprecated since 1.33.0: superseded by trim_start_matches
pub fn trim_left_matches<P>(&self, pat: P) -> &strwhere
P: Pattern,
trim_start_matches
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.
§Examples
assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");
1.0.0 · Sourcepub fn trim_right_matches<P>(&self, pat: P) -> &str
👎Deprecated since 1.33.0: superseded by trim_end_matches
pub fn trim_right_matches<P>(&self, pat: P) -> &str
trim_end_matches
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a
function or closure that determines if a character matches.
§Text directionality
A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.
§Examples
Simple patterns:
assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");
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());
Sourcepub fn as_ascii(&self) -> Option<&[AsciiChar]>
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_ascii(&self) -> Option<&[AsciiChar]>
ascii_char
)If this string slice is_ascii
, returns it as a slice
of ASCII characters, otherwise returns None
.
1.23.0 · Sourcepub fn eq_ignore_ascii_case(&self, other: &str) -> bool
pub fn eq_ignore_ascii_case(&self, other: &str) -> bool
Checks that two strings are an ASCII case-insensitive match.
Same as to_ascii_lowercase(a) == to_ascii_lowercase(b)
,
but without allocating and copying temporaries.
§Examples
assert!("Ferris".eq_ignore_ascii_case("FERRIS"));
assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));
1.23.0 · Sourcepub fn make_ascii_uppercase(&mut self)
pub fn make_ascii_uppercase(&mut self)
Converts this string to its ASCII upper case equivalent in-place.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To return a new uppercased value without modifying the existing one, use
to_ascii_uppercase()
.
§Examples
let mut s = String::from("Grüße, Jürgen ❤");
s.make_ascii_uppercase();
assert_eq!("GRüßE, JüRGEN ❤", s);
1.23.0 · Sourcepub fn make_ascii_lowercase(&mut self)
pub fn make_ascii_lowercase(&mut self)
Converts this string to its ASCII lower case equivalent in-place.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To return a new lowercased value without modifying the existing one, use
to_ascii_lowercase()
.
§Examples
let mut s = String::from("GRÜßE, JÜRGEN ❤");
s.make_ascii_lowercase();
assert_eq!("grÜße, jÜrgen ❤", s);
1.80.0 · Sourcepub fn trim_ascii_start(&self) -> &str
pub fn trim_ascii_start(&self) -> &str
Returns a string slice with leading ASCII whitespace removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(" \t \u{3000}hello world\n".trim_ascii_start(), "\u{3000}hello world\n");
assert_eq!(" ".trim_ascii_start(), "");
assert_eq!("".trim_ascii_start(), "");
1.80.0 · Sourcepub fn trim_ascii_end(&self) -> &str
pub fn trim_ascii_end(&self) -> &str
Returns a string slice with trailing ASCII whitespace removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!("\r hello world\u{3000}\n ".trim_ascii_end(), "\r hello world\u{3000}");
assert_eq!(" ".trim_ascii_end(), "");
assert_eq!("".trim_ascii_end(), "");
1.80.0 · Sourcepub fn trim_ascii(&self) -> &str
pub fn trim_ascii(&self) -> &str
Returns a string slice with leading and trailing ASCII whitespace removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!("\r hello world\n ".trim_ascii(), "hello world");
assert_eq!(" ".trim_ascii(), "");
assert_eq!("".trim_ascii(), "");
1.34.0 · Sourcepub fn escape_debug(&self) -> EscapeDebug<'_>
pub fn escape_debug(&self) -> EscapeDebug<'_>
Returns 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<'_>
Returns 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<'_>
Returns 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}");
Sourcepub fn substr_range(&self, substr: &str) -> Option<Range<usize>>
🔬This is a nightly-only experimental API. (substr_range
)
pub fn substr_range(&self, substr: &str) -> Option<Range<usize>>
substr_range
)Returns the range that a substring points to.
Returns None
if substr
does not point within self
.
Unlike str::find
, this does not search through the string.
Instead, it uses pointer arithmetic to find where in the string
substr
is derived from.
This is useful for extending str::split
and similar methods.
Note that this method may return false positives (typically either
Some(0..0)
or Some(self.len()..self.len())
) if substr
is a
zero-length str
that points at the beginning or end of another,
independent, str
.
§Examples
#![feature(substr_range)]
let data = "a, b, b, a";
let mut iter = data.split(", ").map(|s| data.substr_range(s).unwrap());
assert_eq!(iter.next(), Some(0..1));
assert_eq!(iter.next(), Some(3..4));
assert_eq!(iter.next(), Some(6..7));
assert_eq!(iter.next(), Some(9..10));
Sourcepub fn as_str(&self) -> &str
🔬This is a nightly-only experimental API. (str_as_str
)
pub fn as_str(&self) -> &str
str_as_str
)Returns the same string as a string slice &str
.
This method is redundant when used directly on &str
, but
it helps dereferencing other string-like types to string slices,
for example references to Box<str>
or Arc<str>
.
1.0.0 · Sourcepub fn replace<P>(&self, from: P, to: &str) -> Stringwhere
P: Pattern,
Available on non-no_global_oom_handling
only.
pub fn replace<P>(&self, from: P, to: &str) -> Stringwhere
P: Pattern,
no_global_oom_handling
only.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<P>(&self, pat: P, to: &str, count: usize) -> Stringwhere
P: Pattern,
Available on non-no_global_oom_handling
only.
pub fn replacen<P>(&self, pat: P, to: &str, count: usize) -> Stringwhere
P: Pattern,
no_global_oom_handling
only.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
Available on non-no_global_oom_handling
only.
pub fn to_lowercase(&self) -> String
no_global_oom_handling
only.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
Available on non-no_global_oom_handling
only.
pub fn to_uppercase(&self) -> String
no_global_oom_handling
only.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
Available on non-no_global_oom_handling
only.
pub fn repeat(&self, n: usize) -> String
no_global_oom_handling
only.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
Available on non-no_global_oom_handling
only.
pub fn to_ascii_uppercase(&self) -> String
no_global_oom_handling
only.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
Available on non-no_global_oom_handling
only.
pub fn to_ascii_lowercase(&self) -> String
no_global_oom_handling
only.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());
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