1.0.0[−][src]Struct alloc::string::String
A UTF-8 encoded, growable string.
The String
type is the most common string type that has ownership over the
contents of the string. It has a close relationship with its borrowed
counterpart, the primitive str
.
Examples
You can create a String
from a literal string with String::from
:
let hello = String::from("Hello, world!");
You can append a char
to a String
with the push
method, and
append a &str
with the push_str
method:
let mut hello = String::from("Hello, "); hello.push('w'); hello.push_str("orld!");
If you have a vector of UTF-8 bytes, you can create a String
from it with
the from_utf8
method:
// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so we'll use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart);
UTF-8
String
s are always valid UTF-8. This has a few implications, the first of
which is that if you need a non-UTF-8 string, consider OsString
. It is
similar, but without the UTF-8 constraint. The second implication is that
you cannot index into a String
:
let s = "hello"; println!("The first letter of s is {}", s[0]); // ERROR!!!
Indexing is intended to be a constant-time operation, but UTF-8 encoding
does not allow us to do this. Furthermore, it's not clear what sort of
thing the index should return: a byte, a codepoint, or a grapheme cluster.
The bytes
and chars
methods return iterators over the first
two, respectively.
Deref
String
s implement Deref
<Target=str>
, and so inherit all of str
's
methods. In addition, this means that you can pass a String
to a
function which takes a &str
by using an ampersand (&
):
fn takes_str(s: &str) { } let s = String::from("Hello"); takes_str(&s);
This will create a &str
from the String
and pass it in. This
conversion is very inexpensive, and so generally, functions will accept
&str
s as arguments unless they need a String
for some specific
reason.
In certain cases Rust doesn't have enough information to make this
conversion, known as Deref
coercion. In the following example a string
slice &'a str
implements the trait TraitExample
, and the function
example_func
takes anything that implements the trait. In this case Rust
would need to make two implicit conversions, which Rust doesn't have the
means to do. For that reason, the following example will not compile.
trait TraitExample {} impl<'a> TraitExample for &'a str {} fn example_func<A: TraitExample>(example_arg: A) {} fn main() { let example_string = String::from("example_string"); example_func(&example_string); }
There are two options that would work instead. The first would be to
change the line example_func(&example_string);
to
example_func(example_string.as_str());
, using the method as_str()
to explicitly extract the string slice containing the string. The second
way changes example_func(&example_string);
to
example_func(&*example_string);
. In this case we are dereferencing a
String
to a str
, then referencing the str
back to
&str
. The second way is more idiomatic, however both work to do the
conversion explicitly rather than relying on the implicit conversion.
Representation
A String
is made up of three components: a pointer to some bytes, a
length, and a capacity. The pointer points to an internal buffer String
uses to store its data. The length is the number of bytes currently stored
in the buffer, and the capacity is the size of the buffer in bytes. As such,
the length will always be less than or equal to the capacity.
This buffer is always stored on the heap.
You can look at these with the as_ptr
, len
, and capacity
methods:
use std::mem; let story = String::from("Once upon a time..."); let ptr = story.as_ptr(); let len = story.len(); let capacity = story.capacity(); // story has nineteen bytes assert_eq!(19, len); // Now that we have our parts, we throw the story away. mem::forget(story); // We can re-build a String out of ptr, len, and capacity. This is all // unsafe because we are responsible for making sure the components are // valid: let s = unsafe { String::from_raw_parts(ptr as *mut _, len, capacity) } ; assert_eq!(String::from("Once upon a time..."), s);
If a String
has enough capacity, adding elements to it will not
re-allocate. For example, consider this program:
let mut s = String::new(); println!("{}", s.capacity()); for _ in 0..5 { s.push_str("hello"); println!("{}", s.capacity()); }
This will output the following:
0
5
10
20
20
40
At first, we have no memory allocated at all, but as we append to the
string, it increases its capacity appropriately. If we instead use the
with_capacity
method to allocate the correct capacity initially:
let mut s = String::with_capacity(25); println!("{}", s.capacity()); for _ in 0..5 { s.push_str("hello"); println!("{}", s.capacity()); }
We end up with a different output:
25
25
25
25
25
25
Here, there's no need to allocate more memory inside the loop.
Methods
impl String
[src]
pub const fn new() -> String
[src]
Creates a new empty String
.
Given that the String
is empty, this will not allocate any initial
buffer. While that means that this initial operation is very
inexpensive, it may cause excessive allocation later when you add
data. If you have an idea of how much data the String
will hold,
consider the with_capacity
method to prevent excessive
re-allocation.
Examples
Basic usage:
let s = String::new();
pub fn with_capacity(capacity: usize) -> String
[src]
Creates a new empty String
with a particular capacity.
String
s have an internal buffer to hold their data. The capacity is
the length of that buffer, and can be queried with the capacity
method. This method creates an empty String
, but one with an initial
buffer that can hold capacity
bytes. This is useful when you may be
appending a bunch of data to the String
, reducing the number of
reallocations it needs to do.
If the given capacity is 0
, no allocation will occur, and this method
is identical to the new
method.
Examples
Basic usage:
let mut s = String::with_capacity(10); // The String contains no chars, even though it has capacity for more assert_eq!(s.len(), 0); // These are all done without reallocating... let cap = s.capacity(); for _ in 0..10 { s.push('a'); } assert_eq!(s.capacity(), cap); // ...but this may make the vector reallocate s.push('a');
pub fn from_utf8(vec: Vec<u8>) -> Result<String, FromUtf8Error>
[src]
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 String
s, 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
.
The inverse of this method is as_bytes
.
Errors
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:
// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so we'll use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart);
Incorrect bytes:
// 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.
pub fn from_utf8_lossy<'a>(v: &'a [u8]) -> Cow<'a, str>
[src]
Converts a slice of bytes to a string, including invalid characters.
Strings are 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 strings, however: strings
are required to be 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.
This function returns a Cow<'a, str>
. If our byte slice is invalid
UTF-8, then we need to insert the replacement characters, which will
change the size of the string, and hence, require a String
. But if
it's already valid UTF-8, we don't need a new allocation. This return
type allows us to handle both cases.
Examples
Basic usage:
// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; let sparkle_heart = String::from_utf8_lossy(&sparkle_heart); assert_eq!("💖", sparkle_heart);
Incorrect bytes:
// some invalid bytes let input = b"Hello \xF0\x90\x80World"; let output = String::from_utf8_lossy(input); assert_eq!("Hello �World", output);
pub fn from_utf16(v: &[u16]) -> Result<String, FromUtf16Error>
[src]
Decode a UTF-16 encoded vector v
into a String
, returning Err
if v
contains any invalid data.
Examples
Basic usage:
// 𝄞music let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063]; assert_eq!(String::from("𝄞music"), String::from_utf16(v).unwrap()); // 𝄞mu<invalid>ic let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063]; assert!(String::from_utf16(v).is_err());
pub fn from_utf16_lossy(v: &[u16]) -> String
[src]
Decode a UTF-16 encoded slice v
into a String
, replacing
invalid data with the replacement character (U+FFFD
).
Unlike from_utf8_lossy
which returns a Cow<'a, str>
,
from_utf16_lossy
returns a String
since the UTF-16 to UTF-8
conversion requires a memory allocation.
Examples
Basic usage:
// 𝄞mus<invalid>ic<invalid> let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834]; assert_eq!(String::from("𝄞mus\u{FFFD}ic\u{FFFD}"), String::from_utf16_lossy(v));
pub unsafe fn from_raw_parts(
buf: *mut u8,
length: usize,
capacity: usize
) -> String
[src]
buf: *mut u8,
length: usize,
capacity: usize
) -> String
Creates a new String
from a length, capacity, and pointer.
Safety
This is highly unsafe, due to the number of invariants that aren't checked:
- The memory at
ptr
needs to have been previously allocated by the same allocator the standard library uses. length
needs to be less than or equal tocapacity
.capacity
needs to be the correct value.
Violating these may cause problems like corrupting the allocator's internal data structures.
The ownership of ptr
is effectively transferred to the
String
which may then deallocate, reallocate or change the
contents of memory pointed to by the pointer at will. Ensure
that nothing else uses the pointer after calling this
function.
Examples
Basic usage:
use std::mem; unsafe { let s = String::from("hello"); let ptr = s.as_ptr(); let len = s.len(); let capacity = s.capacity(); mem::forget(s); let s = String::from_raw_parts(ptr as *mut _, len, capacity); assert_eq!(String::from("hello"), s); }
pub unsafe fn from_utf8_unchecked(bytes: Vec<u8>) -> String
[src]
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 details.
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, it may cause
memory unsafety issues with future users of the String
, as the rest of
the standard library assumes that String
s are valid UTF-8.
Examples
Basic usage:
// 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);
pub fn into_bytes(self) -> Vec<u8>
[src]
Converts a String
into a byte vector.
This consumes the String
, so we do not need to copy its contents.
Examples
Basic usage:
let s = String::from("hello"); let bytes = s.into_bytes(); assert_eq!(&[104, 101, 108, 108, 111][..], &bytes[..]);
pub fn as_str(&self) -> &str
1.7.0[src]
Extracts a string slice containing the entire String
.
Examples
Basic usage:
let s = String::from("foo"); assert_eq!("foo", s.as_str());
pub fn as_mut_str(&mut self) -> &mut str
1.7.0[src]
Converts a String
into a mutable string slice.
Examples
Basic usage:
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);
pub fn push_str(&mut self, string: &str)
[src]
Appends a given string slice onto the end of this String
.
Examples
Basic usage:
let mut s = String::from("foo"); s.push_str("bar"); assert_eq!("foobar", s);
pub fn capacity(&self) -> usize
[src]
Returns this String
's capacity, in bytes.
Examples
Basic usage:
let s = String::with_capacity(10); assert!(s.capacity() >= 10);
pub fn reserve(&mut self, additional: usize)
[src]
Ensures that this String
's capacity is at least additional
bytes
larger than its length.
The capacity may be increased by more than additional
bytes if it
chooses, to prevent frequent reallocations.
If you do not want this "at least" behavior, see the reserve_exact
method.
Panics
Panics if the new capacity overflows usize
.
Examples
Basic usage:
let mut s = String::new(); s.reserve(10); assert!(s.capacity() >= 10);
This may 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 10 assert_eq!(2, s.len()); assert_eq!(10, s.capacity()); // Since we already have an extra 8 capacity, calling this... s.reserve(8); // ... doesn't actually increase. assert_eq!(10, s.capacity());
pub fn reserve_exact(&mut self, additional: usize)
[src]
Ensures that this String
's capacity is additional
bytes
larger than its length.
Consider using the reserve
method unless you absolutely know
better than the allocator.
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 may 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 10 assert_eq!(2, s.len()); assert_eq!(10, s.capacity()); // Since we already have an extra 8 capacity, calling this... s.reserve_exact(8); // ... doesn't actually increase. assert_eq!(10, s.capacity());
pub fn try_reserve(
&mut self,
additional: usize
) -> Result<(), CollectionAllocErr>
[src]
&mut self,
additional: usize
) -> Result<(), CollectionAllocErr>
🔬 This is a nightly-only experimental API. (try_reserve
#48043)
new API
Tries to reserve capacity for at least additional
more elements to be inserted
in the given String
. The collection may reserve more space to avoid
frequent reallocations. After calling reserve
, capacity will be
greater than or equal to self.len() + additional
. Does nothing if
capacity is already sufficient.
Errors
If the capacity overflows, or the allocator reports a failure, then an error is returned.
Examples
#![feature(try_reserve)] use std::collections::CollectionAllocErr; fn process_data(data: &str) -> Result<String, CollectionAllocErr> { 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) }
pub fn try_reserve_exact(
&mut self,
additional: usize
) -> Result<(), CollectionAllocErr>
[src]
&mut self,
additional: usize
) -> Result<(), CollectionAllocErr>
🔬 This is a nightly-only experimental API. (try_reserve
#48043)
new API
Tries to reserves the minimum capacity for exactly additional
more elements to
be inserted in the given String
. After calling reserve_exact
,
capacity will be greater than or equal to self.len() + additional
.
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.
Errors
If the capacity overflows, or the allocator reports a failure, then an error is returned.
Examples
#![feature(try_reserve)] use std::collections::CollectionAllocErr; fn process_data(data: &str) -> Result<String, CollectionAllocErr> { 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) }
pub fn shrink_to_fit(&mut self)
[src]
Shrinks the capacity of this String
to match its length.
Examples
Basic usage:
let mut s = String::from("foo"); s.reserve(100); assert!(s.capacity() >= 100); s.shrink_to_fit(); assert_eq!(3, s.capacity());
pub fn shrink_to(&mut self, min_capacity: usize)
[src]
🔬 This is a nightly-only experimental API. (shrink_to
#56431)
new API
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.
Panics if the current capacity is smaller than the supplied minimum capacity.
Examples
#![feature(shrink_to)] 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);
pub fn push(&mut self, ch: char)
[src]
Appends the given char
to the end of this String
.
Examples
Basic usage:
let mut s = String::from("abc"); s.push('1'); s.push('2'); s.push('3'); assert_eq!("abc123", s);
pub fn as_bytes(&self) -> &[u8]
[src]
Returns a byte slice of this String
's contents.
The inverse of this method is from_utf8
.
Examples
Basic usage:
let s = String::from("hello"); assert_eq!(&[104, 101, 108, 108, 111], s.as_bytes());
pub fn truncate(&mut self, new_len: usize)
[src]
Shortens this String
to the specified length.
If new_len
is greater than 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
Basic usage:
let mut s = String::from("hello"); s.truncate(2); assert_eq!("he", s);
pub fn pop(&mut self) -> Option<char>
[src]
Removes the last character from the string buffer and returns it.
Returns None
if this String
is empty.
Examples
Basic usage:
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);
pub fn remove(&mut self, idx: usize) -> char
[src]
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
Basic usage:
let mut s = String::from("foo"); assert_eq!(s.remove(0), 'f'); assert_eq!(s.remove(1), 'o'); assert_eq!(s.remove(0), 'o');
pub fn retain<F>(&mut self, f: F) where
F: FnMut(char) -> bool,
1.26.0[src]
F: FnMut(char) -> bool,
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");
The exact order may be useful for tracking external state, like an index.
let mut s = String::from("abcde"); let keep = [false, true, true, false, true]; let mut i = 0; s.retain(|_| (keep[i], i += 1).0); assert_eq!(s, "bce");
pub fn insert(&mut self, idx: usize, ch: char)
[src]
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
Basic usage:
let mut s = String::with_capacity(3); s.insert(0, 'f'); s.insert(1, 'o'); s.insert(2, 'o'); assert_eq!("foo", s);
pub fn insert_str(&mut self, idx: usize, string: &str)
1.16.0[src]
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
Basic usage:
let mut s = String::from("bar"); s.insert_str(0, "foo"); assert_eq!("foobar", s);
pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8>
[src]
Returns a mutable reference to the contents of this String
.
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, it may cause
memory unsafety issues with future users of the String
, as the rest of
the standard library assumes that String
s are valid UTF-8.
Examples
Basic usage:
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");
pub fn len(&self) -> usize
[src]
Returns the length of this String
, in bytes.
Examples
Basic usage:
let a = String::from("foo"); assert_eq!(a.len(), 3);
pub fn is_empty(&self) -> bool
[src]
Returns true
if this String
has a length of zero, and false
otherwise.
Examples
Basic usage:
let mut v = String::new(); assert!(v.is_empty()); v.push('a'); assert!(!v.is_empty());
pub fn split_off(&mut self, at: usize) -> String
1.16.0[src]
Splits the string into two at the given 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!");
pub fn clear(&mut self)
[src]
Truncates this String
, removing all contents.
While this means the String
will have a length of zero, it does not
touch its capacity.
Examples
Basic usage:
let mut s = String::from("foo"); s.clear(); assert!(s.is_empty()); assert_eq!(0, s.len()); assert_eq!(3, s.capacity());
ⓘImportant traits for Drain<'_>pub fn drain<R>(&mut self, range: R) -> Drain where
R: RangeBounds<usize>,
1.6.0[src]
R: RangeBounds<usize>,
Creates a draining iterator that removes the specified range in the String
and yields the removed chars
.
Note: The element range is removed even if the iterator is not consumed until the end.
Panics
Panics if the starting point or end point do not lie on a char
boundary, or if they're out of bounds.
Examples
Basic usage:
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, "");
pub fn replace_range<R>(&mut self, range: R, replace_with: &str) where
R: RangeBounds<usize>,
1.27.0[src]
R: RangeBounds<usize>,
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
Basic usage:
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");
ⓘImportant traits for Box<I>pub fn into_boxed_str(self) -> Box<str>
1.4.0[src]
Trait Implementations
impl ToString for String
1.17.0[src]
impl Deref for String
[src]
impl DerefMut for String
1.3.0[src]
impl PartialEq<String> for String
[src]
impl<'a, 'b> PartialEq<str> for String
[src]
impl<'a, 'b> PartialEq<String> for str
[src]
impl<'a, 'b> PartialEq<&'a str> for String
[src]
impl<'a, 'b> PartialEq<String> for &'a str
[src]
impl<'a, 'b> PartialEq<String> for Cow<'a, str>
[src]
impl<'a, 'b> PartialEq<Cow<'a, str>> for String
[src]
impl Eq for String
[src]
impl Ord for String
[src]
fn cmp(&self, other: &String) -> Ordering
[src]
fn max(self, other: Self) -> Self
1.21.0[src]
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
1.21.0[src]
Compares and returns the minimum of two values. Read more
fn clamp(self, min: Self, max: Self) -> Self
[src]
Restrict a value to a certain interval. Read more
impl PartialOrd<String> for String
[src]
fn partial_cmp(&self, other: &String) -> Option<Ordering>
[src]
fn lt(&self, other: &String) -> bool
[src]
fn le(&self, other: &String) -> bool
[src]
fn gt(&self, other: &String) -> bool
[src]
fn ge(&self, other: &String) -> bool
[src]
impl Hash for String
[src]
fn hash<H: Hasher>(&self, hasher: &mut H)
[src]
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
1.3.0[src]
H: Hasher,
Feeds a slice of this type into the given [Hasher
]. Read more
impl Display for String
[src]
impl Debug for String
[src]
impl<'a, 'b> Pattern<'a> for &'b String
[src]
A convenience impl that delegates to the impl for &str
type Searcher = <&'b str as Pattern<'a>>::Searcher
🔬 This is a nightly-only experimental API. (pattern
#27721)
API not fully fleshed out and ready to be stabilized
Associated searcher for this pattern
fn into_searcher(self, haystack: &'a str) -> <&'b str as Pattern<'a>>::Searcher
[src]
fn is_contained_in(self, haystack: &'a str) -> bool
[src]
fn is_prefix_of(self, haystack: &'a str) -> bool
[src]
fn is_suffix_of(self, haystack: &'a str) -> bool where
Self::Searcher: ReverseSearcher<'a>,
[src]
Self::Searcher: ReverseSearcher<'a>,
🔬 This is a nightly-only experimental API. (pattern
#27721)
API not fully fleshed out and ready to be stabilized
Checks whether the pattern matches at the back of the haystack
impl FromStr for String
[src]
type Err = Infallible
The associated error which can be returned from parsing.
fn from_str(s: &str) -> Result<String, ParseError>
[src]
impl<'_> Add<&'_ str> for String
[src]
Implements the +
operator for concatenating two strings.
This consumes the String
on the left-hand side and re-uses its buffer (growing it if
necessary). This is done to avoid allocating a new String
and copying the entire contents on
every operation, which would lead to O(n^2)
running time when building an n
-byte string by
repeated concatenation.
The string on the right-hand side is only borrowed; its contents are copied into the returned
String
.
Examples
Concatenating two String
s takes the first by value and borrows the second:
let a = String::from("hello"); let b = String::from(" world"); let c = a + &b; // `a` is moved and can no longer be used here.
If you want to keep using the first String
, you can clone it and append to the clone instead:
let a = String::from("hello"); let b = String::from(" world"); let c = a.clone() + &b; // `a` is still valid here.
Concatenating &str
slices can be done by converting the first to a String
:
let a = "hello"; let b = " world"; let c = a.to_string() + b;
type Output = String
The resulting type after applying the +
operator.
fn add(self, other: &str) -> String
[src]
impl<'_> AddAssign<&'_ str> for String
1.12.0[src]
Implements the +=
operator for appending to a String
.
This has the same behavior as the push_str
method.
fn add_assign(&mut self, other: &str)
[src]
impl Index<Range<usize>> for String
[src]
type Output = str
The returned type after indexing.
fn index(&self, index: Range<usize>) -> &str
[src]
impl Index<RangeTo<usize>> for String
[src]
type Output = str
The returned type after indexing.
fn index(&self, index: RangeTo<usize>) -> &str
[src]
impl Index<RangeFrom<usize>> for String
[src]
type Output = str
The returned type after indexing.
fn index(&self, index: RangeFrom<usize>) -> &str
[src]
impl Index<RangeFull> for String
[src]
impl Index<RangeInclusive<usize>> for String
1.26.0[src]
type Output = str
The returned type after indexing.
fn index(&self, index: RangeInclusive<usize>) -> &str
[src]
impl Index<RangeToInclusive<usize>> for String
1.26.0[src]
type Output = str
The returned type after indexing.
fn index(&self, index: RangeToInclusive<usize>) -> &str
[src]
impl IndexMut<Range<usize>> for String
1.3.0[src]
impl IndexMut<RangeTo<usize>> for String
1.3.0[src]
impl IndexMut<RangeFrom<usize>> for String
1.3.0[src]
impl IndexMut<RangeFull> for String
1.3.0[src]
impl IndexMut<RangeInclusive<usize>> for String
1.26.0[src]
fn index_mut(&mut self, index: RangeInclusive<usize>) -> &mut str
[src]
impl IndexMut<RangeToInclusive<usize>> for String
1.26.0[src]
fn index_mut(&mut self, index: RangeToInclusive<usize>) -> &mut str
[src]
impl Extend<char> for String
[src]
fn extend<I: IntoIterator<Item = char>>(&mut self, iter: I)
[src]
impl<'a> Extend<&'a char> for String
1.2.0[src]
fn extend<I: IntoIterator<Item = &'a char>>(&mut self, iter: I)
[src]
impl<'a> Extend<&'a str> for String
[src]
fn extend<I: IntoIterator<Item = &'a str>>(&mut self, iter: I)
[src]
impl Extend<String> for String
1.4.0[src]
fn extend<I: IntoIterator<Item = String>>(&mut self, iter: I)
[src]
impl<'a> Extend<Cow<'a, str>> for String
1.19.0[src]
fn extend<I: IntoIterator<Item = Cow<'a, str>>>(&mut self, iter: I)
[src]
impl FromIterator<char> for String
[src]
fn from_iter<I: IntoIterator<Item = char>>(iter: I) -> String
[src]
impl<'a> FromIterator<&'a char> for String
1.17.0[src]
fn from_iter<I: IntoIterator<Item = &'a char>>(iter: I) -> String
[src]
impl<'a> FromIterator<&'a str> for String
[src]
fn from_iter<I: IntoIterator<Item = &'a str>>(iter: I) -> String
[src]
impl FromIterator<String> for String
1.4.0[src]
fn from_iter<I: IntoIterator<Item = String>>(iter: I) -> String
[src]
impl<'a> FromIterator<Cow<'a, str>> for String
1.19.0[src]
fn from_iter<I: IntoIterator<Item = Cow<'a, str>>>(iter: I) -> String
[src]
impl<'a> FromIterator<String> for Cow<'a, str>
1.12.0[src]
fn from_iter<I: IntoIterator<Item = String>>(it: I) -> Cow<'a, str>
[src]
impl Write for String
[src]
fn write_str(&mut self, s: &str) -> Result
[src]
fn write_char(&mut self, c: char) -> Result
[src]
fn write_fmt(&mut self, args: Arguments) -> Result<(), Error>
[src]
Glue for usage of the [write!
] macro with implementors of this trait. Read more
impl AsRef<str> for String
[src]
impl AsRef<[u8]> for String
[src]
impl From<String> for Arc<str>
1.21.0[src]
impl From<String> for Rc<str>
1.21.0[src]
impl<'_> From<&'_ str> for String
[src]
impl<'_> From<&'_ String> for String
1.35.0[src]
impl From<Box<str>> for String
1.18.0[src]
fn from(s: Box<str>) -> String
[src]
Converts the given boxed str
slice to a String
.
It is notable that the str
slice is owned.
Examples
Basic usage:
let s1: String = String::from("hello world"); let s2: Box<str> = s1.into_boxed_str(); let s3: String = String::from(s2); assert_eq!("hello world", s3)
impl From<String> for Box<str>
1.20.0[src]
ⓘImportant traits for Box<I>fn from(s: String) -> Box<str>
[src]
Converts the given String
to a boxed str
slice that is owned.
Examples
Basic usage:
let s1: String = String::from("hello world"); let s2: Box<str> = Box::from(s1); let s3: String = String::from(s2); assert_eq!("hello world", s3)
impl<'a> From<Cow<'a, str>> for String
1.14.0[src]
impl<'a> From<String> for Cow<'a, str>
[src]
impl<'a> From<&'a String> for Cow<'a, str>
1.28.0[src]
impl From<String> for Vec<u8>
1.14.0[src]
fn from(string: String) -> Vec<u8>
[src]
Converts the given String
to a vector Vec
that holds values of type u8
.
Examples
Basic usage:
let s1 = String::from("hello world"); let v1 = Vec::from(s1); for b in v1 { println!("{}", b); }
impl Clone for String
[src]
fn clone(&self) -> Self
[src]
fn clone_from(&mut self, source: &Self)
[src]
impl Default for String
[src]
impl Borrow<str> for String
[src]
impl BorrowMut<str> for String
1.36.0[src]
fn borrow_mut(&mut self) -> &mut str
[src]
Auto Trait Implementations
Blanket Implementations
impl<T> ToOwned for T where
T: Clone,
[src]
T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&Self) -> T
[src]
fn clone_into(&Self, &mut T)
[src]
impl<T> ToString for T where
T: Display + ?Sized,
[src]
T: Display + ?Sized,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
[src]
U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
[src]
impl<T, U> Into<U> for T where
U: From<T>,
[src]
U: From<T>,
impl<T> From<T> for T
[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
[src]
U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
[src]
impl<T> Borrow<T> for T where
T: ?Sized,
[src]
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]
T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
[src]
impl<T> Any for T where
T: 'static + ?Sized,
[src]
T: 'static + ?Sized,