Struct staticvec::StaticString

pub struct StaticString<const N: usize> { /* fields omitted */ }

A fixed-capacity String-like struct built around an instance of StaticVec<u8, N>.

Examples

use staticvec::{StaticString, StringError};

#[derive(Debug)]
pub struct User {
  pub username: StaticString<20>,
  pub role: StaticString<5>,
}

fn main() -> Result<(), StringError> {
  let user = User {
    username: StaticString::try_from_str("user")?,
    role: StaticString::try_from_str("admin")?,
  };
  println!("{:?}", user);
  Ok(())
}

Implementations

impl<const N: usize> StaticString<N>

pub const fn new() -> Self

Returns a new StaticString instance.

Example usage:

let string = StaticString::<20>::new();
assert!(string.is_empty());

pub unsafe fn from_str_unchecked(string: &str) -> Self

Creates a new StaticString instance from string, without doing any checking to ensure that the length of string does not exceed the resulting StaticString’s declared capacity.

Safety

The length of string must not exceed the declared capacity of the StaticString being created, as this would result in writing to an out-of-bounds memory region.

Example usage:

let string = unsafe { StaticString::<20>::from_str_unchecked("My String") };
assert_eq!(string, "My String");

pub fn from_str<S: AsRef<str>>(string: S) -> Self

Creates a new StaticString from string, truncating string as necessary if it has a length greater than the StaticString’s declared capacity.

Example usage:

let string = StaticString::<20>::from_str("My String");
assert_eq!(string, "My String");
let truncate = "0".repeat(21);
let truncated = "0".repeat(20);
let string = StaticString::<20>::from_str(&truncate);
assert_eq!(string, truncated.as_str());

pub fn try_from_str<S: AsRef<str>>(string: S) -> Result<Self, CapacityError<N>>

Creates a new StaticString from string if the length of string is less than or equal to the StaticString’s declared capacity, or returns a CapacityError otherwise.

Example usage:

let string = StaticString::<20>::from("My String");
assert_eq!(string.as_str(), "My String");
assert_eq!(StaticString::<20>::try_from_str("").unwrap().as_str(), "");
let out_of_bounds = "0".repeat(21);
assert!(StaticString::<20>::try_from_str(out_of_bounds).is_err());

pub fn from_iterator<U: AsRef<str>, I: IntoIterator<Item = U>>(iter: I) -> Self

Creates a new StaticString from the contents of an iterator, returning immediately if and when the StaticString reaches maximum capacity regardless of whether or not the iterator still has more items to yield.

Example usage:

let string = StaticString::<300>::from_iterator(&["My String", " Other String"][..]);
assert_eq!(string.as_str(), "My String Other String");
let out_of_bounds = (0..400).map(|_| "000");
let truncated = "0".repeat(18);
let truncate = StaticString::<20>::from_iterator(out_of_bounds);
assert_eq!(truncate.as_str(), truncated.as_str());

pub fn try_from_iterator<U: AsRef<str>, I: IntoIterator<Item = U>>(
    iter: I
) -> Result<Self, CapacityError<N>>

Creates a new StaticString from the contents of an iterator if the iterator has a length less than or equal to the StaticString’s declared capacity, or returns a CapacityError otherwise.

Example usage:

let string = StaticString::<300>::try_from_iterator(
  &["My String", " My Other String"][..]
).unwrap();
assert_eq!(string.as_str(), "My String My Other String");
let out_of_bounds = (0..100).map(|_| "000");
assert!(StaticString::<20>::try_from_iterator(out_of_bounds).is_err());

pub fn from_chars<I: IntoIterator<Item = char>>(iter: I) -> Self

Creates a new StaticString from the contents of a char iterator, returning immediately if and when the StaticString reaches maximum capacity regardless of whether or not the iterator still has more items to yield.

let string = StaticString::<20>::from_chars("My String".chars());
assert_eq!(string, "My String");
let out_of_bounds = "0".repeat(21);
let truncated = "0".repeat(20);
let truncate = StaticString::<20>::from_chars(out_of_bounds.chars());
assert_eq!(truncate.as_str(), truncated.as_str());

pub fn try_from_chars<I: IntoIterator<Item = char>>(
    iter: I
) -> Result<Self, StringError>

Creates a new StaticString from the contents of a char iterator if the iterator has a length less than or equal to the StaticString’s declared capacity, or returns StringError::OutOfBounds otherwise.

Example usage:

let string = StaticString::<20>::try_from_chars("My String".chars())?;
assert_eq!(string.as_str(), "My String");
let out_of_bounds = "0".repeat(21);
assert!(StaticString::<20>::try_from_chars(out_of_bounds.chars()).is_err());

pub unsafe fn from_utf8_unchecked<B: AsRef<[u8]>>(slice: B) -> Self

Creates a new StaticString instance from the provided byte slice, without doing any checking to ensure that the slice contains valid UTF-8 data and has a length less than or equal to the declared capacity of the StaticString.

Safety

The length of the slice must not exceed the declared capacity of the StaticString being created, as this would result in writing to an out-of-bounds memory region.

The slice must also contain strictly valid UTF-8 data, as if it does not, various assumptions made in the internal implementation of StaticString will be silently invalidated, almost certainly eventually resulting in undefined behavior.

Example usage:

let string = unsafe { StaticString::<20>::from_utf8_unchecked("My String") };
assert_eq!(string, "My String");
// Undefined behavior, don't do it:
// let out_of_bounds = "0".repeat(300);
// let ub = unsafe { StaticString::<20>::from_utf8_unchecked(out_of_bounds)) };

pub fn from_utf8<B: AsRef<[u8]>>(slice: B) -> Result<Self, StringError>

Creates a new StaticString instance from the provided byte slice, returning StringError::Utf8 on invalid UTF-8 data, and truncating the input slice as necessary if it has a length greater than the declared capacity of the StaticString being created.

Example usage:

let string = StaticString::<20>::from_utf8("My String")?;
assert_eq!(string, "My String");
let invalid_utf8 = [0, 159, 146, 150];
assert!(StaticString::<20>::from_utf8(invalid_utf8).unwrap_err().is_utf8());
let out_of_bounds = "0".repeat(300);
assert_eq!(StaticString::<20>::from_utf8(out_of_bounds.as_bytes())?.as_str(), "0".repeat(20).as_str());

pub fn try_from_utf8<B: AsRef<[u8]>>(slice: B) -> Result<Self, StringError>

Creates a new StaticString from the provided byte slice, returning StringError::Utf8 on invalid UTF-8 data or StringError::OutOfBounds if the slice has a length greater than the StaticString’s declared capacity.

Example usage:

let string = StaticString::<20>::try_from_utf8("My String")?;
assert_eq!(string, "My String");
let invalid_utf8 = [0, 159, 146, 150];
assert!(StaticString::<20>::try_from_utf8(invalid_utf8).unwrap_err().is_utf8());
let out_of_bounds = "0000".repeat(400);
assert!(StaticString::<20>::try_from_utf8(out_of_bounds.as_bytes()).unwrap_err().is_out_of_bounds());

pub fn from_utf16_lossy<B: AsRef<[u16]>>(slice: B) -> Self

Creates a new StaticString instance from the provided u16 slice, replacing invalid UTF-16 data with REPLACEMENT_CHARACTER (�), and truncating the input slice as necessary if it has a length greater than the declared capacity of the StaticString being created.

Example usage:

let music = [0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063];
let string = StaticString::<20>::from_utf16_lossy(music);
assert_eq!(string, "𝄞music");
let invalid_utf16 = [0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
assert_eq!(StaticString::<20>::from_utf16_lossy(invalid_utf16).as_str(), "𝄞mu\u{FFFD}ic");
let out_of_bounds: Vec<u16> = (0..300).map(|_| 0).collect();
assert_eq!(StaticString::<20>::from_utf16_lossy(&out_of_bounds).as_str(), "\0".repeat(20).as_str());

pub fn from_utf16<B: AsRef<[u16]>>(slice: B) -> Result<Self, StringError>

Creates a new StaticString instance from the provided u16 slice, returning StringError::Utf16 on invalid UTF-16 data, and truncating the input slice as necessary if it has a length greater than the declared capacity of the StaticString being created.

Example usage:

let music = [0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063];
let string = StaticString::<20>::from_utf16(music)?;
assert_eq!(string.as_str(), "𝄞music");
let invalid_utf16 = [0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
assert!(StaticString::<20>::from_utf16(invalid_utf16).unwrap_err().is_utf16());
let out_of_bounds: Vec<u16> = (0..300).map(|_| 0).collect();
assert_eq!(StaticString::<20>::from_utf16(out_of_bounds)?.as_str(),
           "\0".repeat(20).as_str());

pub fn try_from_utf16<B: AsRef<[u16]>>(slice: B) -> Result<Self, StringError>

Creates a new StaticString from the provided u16 slice, returning StringError::Utf16 on invalid UTF-16 data or StringError::OutOfBounds if the slice has a length greater than the declared capacity of the StaticString being created.

Example usage:

let music = [0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063];
let string = StaticString::<20>::try_from_utf16(music)?;
assert_eq!(string.as_str(), "𝄞music");
let invalid_utf16 = [0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
assert!(StaticString::<20>::try_from_utf16(invalid_utf16).unwrap_err().is_utf16());
let out_of_bounds: StaticVec<u16, 300> = (0..300).map(|_| 0).collect();
assert!(StaticString::<20>::try_from_utf16(out_of_bounds).unwrap_err().is_out_of_bounds());

pub const fn as_str(&self) -> &str

Extracts a str slice containing the entire contents of the StaticString.

Example usage:

let s = StaticString::<20>::from_str("My String");
assert_eq!(s.as_str(), "My String");

pub const fn as_mut_str(&mut self) -> &mut str

Extracts a mutable str slice containing the entire contents of the StaticString.

Example usage:

let mut s = StaticString::<20>::from_str("My String");
assert_eq!(s.as_mut_str(), "My String");

pub const fn as_bytes(&self) -> &[u8]

Extracts a u8 slice containing the entire contents of the StaticString.

Example usage:

let s = StaticString::<20>::from_str("My String");
assert_eq!(s.as_bytes(), "My String".as_bytes());

pub fn into_bytes(self) -> StaticVec<u8, N>

Returns the StaticString’s internal instance of StaticVec<u8, N>. Note that using this function consumes the StaticString.

Example usage:

let s = StaticString::<5>::from("hello");
let bytes = s.into_bytes();
assert_eq!(&bytes[..], &[104, 101, 108, 108, 111][..]);

pub const unsafe fn as_mut_bytes(&mut self) -> &mut [u8]

Extracts a mutable u8 slice containing the entire contents of the StaticString.

Safety

Care must be taken to ensure that the returned u8 slice is not mutated in such a way that it no longer amounts to valid UTF-8.

Example usage:

let mut s = StaticString::<20>::try_from_str("My String")?;
assert_eq!(unsafe { s.as_mut_bytes() }, "My String".as_bytes());

pub const unsafe fn as_mut_staticvec(&mut self) -> &mut StaticVec<u8, N>

Returns a mutable reference to the StaticString’s backing StaticVec.

Safety

Care must be taken to ensure that the returned StaticVec reference is not mutated in such a way that it no longer contains valid UTF-8.

Example usage:

let mut s = StaticString::<20>::try_from_str("My String")?;
assert_eq!(unsafe { s.as_mut_staticvec() }, "My String".as_bytes());

pub const fn capacity(&self) -> usize

Returns the total capacity of the StaticString. This is always equivalent to the generic N parameter it was declared with, which determines the fixed size of the backing StaticVec instance.

Example usage:

assert_eq!(StaticString::<32>::new().capacity(), 32);

pub const fn remaining_capacity(&self) -> usize

Returns the remaining capacity (which is to say, self.capacity() - self.len()) of the StaticString.

Example usage:

assert_eq!(StaticString::<32>::from("abcd").remaining_capacity(), 28);

pub const unsafe fn push_str_unchecked(&mut self, string: &str)

Pushes string to the StaticString without doing any checking to ensure that self.len() + string.len() does not exceed the StaticString’s total capacity.

Safety

self.len() + string.len() must not exceed the total capacity of the StaticString instance, as this would result in writing to an out-of-bounds memory region.

Example usage:

let mut s = StaticString::<6>::from("foo");
unsafe { s.push_str_unchecked("bar") };
assert_eq!(s, "foobar");

pub fn push_str<S: AsRef<str>>(&mut self, string: S)

Attempts to push string to the StaticString, panicking if it is the case that self.len() + string.len() exceeds the StaticString’s total capacity.

Example usage:

let mut s = StaticString::<6>::from("foo");
s.push_str("bar");
assert_eq!(s, "foobar");

pub fn push_str_truncating<S: AsRef<str>>(&mut self, string: S)

Attempts to push string to the StaticString. Truncates string as necessary (or simply does nothing at all) if it is the case that self.len() + string.len() exceeds the StaticString’s total capacity.

Example usage:

let mut s = StaticString::<300>::try_from_str("My String")?;
s.push_str_truncating(" My other String");
assert_eq!(s.as_str(), "My String My other String");
let mut s = StaticString::<20>::new();
s.push_str_truncating("0".repeat(21));
assert_eq!(s.as_str(), "0".repeat(20).as_str());

pub fn try_push_str<S: AsRef<str>>(
    &mut self,
    string: S
) -> Result<(), CapacityError<N>>

Pushes string to the StaticString if self.len() + string.len() does not exceed the StaticString’s total capacity, or returns a CapacityError otherwise.

Example usage:

let mut s = StaticString::<300>::from("My String");
s.try_push_str(" My other String").unwrap();
assert_eq!(s.as_str(), "My String My other String");
assert!(s.try_push_str("0".repeat(300)).is_err());

pub unsafe fn push_unchecked(&mut self, character: char)

Appends the given char to the end of the StaticString without doing any checking to ensure that self.len() + character.len_utf8() does not exceed the total capacity of the StaticString instance.

Safety

self.len() + character.len_utf8() must not exceed the total capacity of the StaticString instance, as this would result in writing to an out-of-bounds memory region.

Example usage:

let mut s = StaticString::<20>::try_from_str("My String")?;
unsafe { s.push_unchecked('!') };
assert_eq!(s.as_str(), "My String!");
// Undefined behavior, don't do it:
// s = StaticString::<20>::try_from_str(&"0".repeat(20))?;
// s.push_unchecked('!');

pub fn push(&mut self, character: char)

Appends the given char to the end of the StaticString, panicking if the StaticString is already at maximum capacity.

Example usage:

let mut string = StaticString::<2>::new();
string.push('a');
string.push('b');
assert_eq!(&string[..], "ab");

pub fn try_push(&mut self, character: char) -> Result<(), StringError>

Appends the given char to the end of the StaticString, returning StringError::OutOfBounds if the StaticString is already at maximum capacity.

Example usage:

let mut s = StaticString::<20>::try_from_str("My String")?;
s.try_push('!')?;
assert_eq!(s.as_str(), "My String!");
let mut s = StaticString::<20>::try_from_str(&"0".repeat(20))?;
assert!(s.try_push('!').is_err());

pub fn truncate(&mut self, new_len: usize)

Truncates the StaticString to new_len if new_len is less than or equal to the StaticString’s current length, or does nothing otherwise. Panics if new_len does not lie at a valid UTF-8 character boundary.

Example usage:

let mut s = StaticString::<20>::from("My String");
s.truncate(5);
assert_eq!(s, "My St");
// Does nothing
s.truncate(6);
assert_eq!(s, "My St");
// Would panic
// let mut s2 = StaticString::<20>::from("🤔");
// s2.truncate(1);

pub fn pop(&mut self) -> Option<char>

Returns the last character in the StaticString in Some if the StaticString’s current length is greater than zero, or None otherwise.

Example usage:

let mut s = StaticString::<20>::try_from_str("A🤔")?;
assert_eq!(s.pop(), Some('🤔'));
assert_eq!(s.pop(), Some('A'));
assert_eq!(s.pop(), None);

pub fn trim(&mut self)

Removes all whitespace from the beginning and end of the StaticString, if any is present.

Example usage:

let mut string = StaticString::<300>::try_from_str("   to be trimmed     ")?;
string.trim();
assert_eq!(string.as_str(), "to be trimmed");
let mut string = StaticString::<20>::try_from_str("   🤔")?;
string.trim();
assert_eq!(string.as_str(), "🤔");

pub fn remove(&mut self, index: usize) -> char

Removes the char at index from the StaticString if index is both less than self.len() and also lies at a valid UTF-8 character boundary, or panics otherwise.

Example usage:

let mut s = StaticString::<20>::from("ABCD🤔");
assert_eq!(s.remove(0), 'A');
assert!(s == "BCD🤔");
assert_eq!(s.remove(2), 'D');
assert!(s == "BC🤔");

pub fn remove_matches<'a, P: for<'x> Pattern<'x>>(&'a mut self, pat: P)

Removes all matches of pattern pat in the StaticString.

Example usage:

let mut s = staticstring!("Trees are not green, the sky is not blue.");
s.remove_matches("not ");
assert_eq!("Trees are green, the sky is blue.", s.as_str());

Matches will be detected and removed iteratively, so in cases where patterns overlap, only the first pattern will be removed:

let mut s = staticstring!("banana");
s.remove_matches("ana");
assert_eq!("bna", s.as_str());

pub fn retain<F: FnMut(char) -> bool>(&mut self, f: F)

Removes all characters from the StaticString except for those specified by the predicate function.

Example usage:

let mut s = StaticString::<20>::from("ABCD🤔");
s.retain(|c| c != '🤔');
assert_eq!(s, "ABCD");

pub unsafe fn insert_unchecked(&mut self, index: usize, character: char)

Inserts character at index, shifting any values that exist in positions greater than index to the right.

Does not do any checking to ensure that character.len_utf8() + self.len() does not exceed the total capacity of the StaticString or that index lies at a valid UTF-8 character boundary.

Safety

The length of the StaticString prior to calling this function must be less than its total capacity, as if this in not the case it will result in writing to an out-of-bounds memory region.

Index must also lie at a valid UTF-8 character boundary, as if it does not, various assumptions made in the internal implementation of StaticString will be silently invalidated, almost certainly eventually resulting in undefined behavior.

Example usage:

let mut s = StaticString::<20>::try_from_str("ABCD🤔")?;
unsafe { s.insert_unchecked(1, 'A') };
unsafe { s.insert_unchecked(1, 'B') };
assert_eq!(s.as_str(), "ABABCD🤔");
// Undefined behavior, don't do it:
// s.insert(20, 'C');
// s.insert(8, 'D');

pub fn try_insert(
    &mut self,
    index: usize,
    character: char
) -> Result<(), StringError>

Inserts character at index, shifting any values that exist in positions greater than index to the right.

Returns StringError::OutOfBounds if character.len_utf8() + self.len() exceeds the total capacity of the StaticString and StringError::NotCharBoundary if index does not lie at a valid UTF-8 character boundary.

Example usage:

let mut s = StaticString::<20>::try_from_str("ABCD🤔")?;
s.try_insert(1, 'E')?;
s.try_insert(2, 'F')?;
assert_eq!(s.as_str(), "AEFBCD🤔");
assert!(s.try_insert(20, 'C').unwrap_err().is_not_char_boundary());
assert!(s.try_insert(8, 'D').unwrap_err().is_not_char_boundary());
let mut s = StaticString::<20>::try_from_str(&"0".repeat(20))?;
assert!(s.try_insert(0, 'C').unwrap_err().is_out_of_bounds());

pub fn insert(&mut self, index: usize, character: char)

Inserts character at index, shifting any values that exist in positions greater than index to the right.

Panics if character.len_utf8() + self.len() exceeds the total capacity of the StaticString or if index does not lie at a valid UTF-8 character boundary.

Example usage:

let mut s = StaticString::<3>::new();
s.insert(0, 'f');
s.insert(1, 'o');
s.insert(2, 'o');
assert_eq!(s, "foo");

pub unsafe fn insert_str_unchecked<S: AsRef<str>>(
    &mut self,
    index: usize,
    string: S
)

Inserts string at index, shifting any values that exist in positions greater than index to the right.

Does not do any checking to ensure that self.len() + string.len() does not exceed the total capacity of the StaticString or that index lies at a valid UTF-8 character boundary.

Safety

self.len() + string.len() must not exceed the total capacity of the StaticString instance, as this would result in writing to an out-of-bounds memory region.

Index must also lie at a valid UTF-8 character boundary, as if it does not, various assumptions made in the internal implementation of StaticString will be silently invalidated, almost certainly eventually resulting in undefined behavior.

Example usage:

let mut s = StaticString::<20>::from_str("ABCD🤔");
unsafe { s.insert_str_unchecked(1, "AB") };
unsafe { s.insert_str_unchecked(1, "BC") };
assert_eq!(s, "ABCABBCD🤔");
// Undefined behavior, don't do it:
// unsafe { s.insert_str_unchecked(20, "C") };
// unsafe { s.insert_str_unchecked(10, "D") };
// unsafe { s.insert_str_unchecked(1, "0".repeat(20)) };

pub fn insert_str<S: AsRef<str>>(&mut self, index: usize, string: S)

Inserts string at index, shifting any values that exist in positions greater than index to the right.

Panics if index is greater than the length of the StaticString or if it does not lie at a valid UTF-8 character boundary, as well as if string.len() + self.len() exceeds the total capacity of the StaticString.

Example usage:

let mut s = StaticString::<20>::from("ABCD🤔");
s.insert_str(1, "AB");
s.insert_str(1, "BC");
assert_eq!(s.as_str(), "ABCABBCD🤔");

pub fn try_insert_str<S: AsRef<str>>(
    &mut self,
    index: usize,
    string: S
) -> Result<(), StringError>

Inserts string at index, shifting any values that exist in positions greater than index to the right.

Returns StringError::OutOfBounds if self.len() + string.len() exceeds the total capacity of the StaticString and StringError::NotCharBoundary if index does not lie at a valid UTF-8 character boundary.

Example usage:

let mut string = StaticString::<20>::try_from_str("ABCD🤔")?;
string.try_insert_str(1, "AB")?;
string.try_insert_str(1, "BC")?;
assert!(string.try_insert_str(1, "0".repeat(20)).unwrap_err().is_out_of_bounds());
assert_eq!(string.as_str(), "ABCABBCD🤔");
assert!(string.try_insert_str(20, "C").unwrap_err().is_not_char_boundary());
assert!(string.try_insert_str(10, "D").unwrap_err().is_not_char_boundary());

pub const fn len(&self) -> usize

Returns the current length of the StaticString.

Example usage:

let mut s = StaticString::<20>::from("ABCD");
assert_eq!(s.len(), 4);
s.push('🤔');
assert_eq!(s.len(), 8);

pub const fn is_empty(&self) -> bool

Returns true if the StaticString has a current length of 0.

Example usage:

let mut s = staticstring!("ABCD");
assert!(!s.is_empty());
s.clear();
assert!(s.is_empty());

pub const fn is_full(&self) -> bool

Returns true if the StaticString’s length is equal to its capacity.

Example usage:

let mut s = staticstring!("ABCD");
assert!(s.is_full());
s.clear();
assert!(!s.is_full());

pub fn split_off(&mut self, at: usize) -> Self

Splits the StaticString in two if at is less than the its current length.

The original StaticString will contain elements 0..at, and the new one will contain elements at..self.len().

Panics if at is greater than the length of the StaticString or if it does not lie at a valid UTF-8 character boundary.

Example usage:

let mut ab = StaticString::<4>::from("ABCD");
let cd = ab.split_off(2);
assert_eq!(ab, "AB");
assert_eq!(cd, "CD");

pub fn clear(&mut self)

Removes all contents from the StaticString and sets its length back to zero.

Example usage:

let mut s = StaticString::<20>::try_from_str("ABCD")?;
assert!(!s.is_empty());
s.clear();
assert!(s.is_empty());

pub fn replace_range<S: AsRef<str>, R: RangeBounds<usize>>(
    &mut self,
    range: R,
    with: S
)

Removes the specified range from the StaticString and replaces it with the provided input (which does not need to have the same length as the range being removed), panicking if either the high or low bounds of the range exceed self.len() or do not lie at valid UTF-8 character boundaries.

Example usage:

let mut s = StaticString::<20>::from("ABCD🤔");
s.replace_range(2..4, "EFGHI");
assert_eq!(s.as_str(), "ABEFGHI🤔");

Methods from Deref<Target = str>

pub fn len(&self) -> usize

Returns the length of self.

This length is in bytes, not chars or graphemes. In other words, it may not be what a human considers the length of the string.

Examples

Basic usage:

let len = "foo".len();
assert_eq!(3, len);

assert_eq!("ƒoo".len(), 4); // fancy f!
assert_eq!("ƒoo".chars().count(), 3);

pub fn is_empty(&self) -> bool

Returns true if self has a length of zero bytes.

Examples

Basic usage:

let s = "";
assert!(s.is_empty());

let s = "not empty";
assert!(!s.is_empty());

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));

pub fn as_bytes(&self) -> &[u8]

Converts a string slice to a byte slice. To convert the byte slice back into a string slice, use the from_utf8 function.

Examples

Basic usage:

let bytes = "bors".as_bytes();
assert_eq!(b"bors", bytes);

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);

pub fn as_ptr(&self) -> *const u8

Converts a string slice to a raw pointer.

As string slices are a slice of bytes, the raw pointer points to a u8. This pointer will be pointing to the first byte of the string slice.

The caller must ensure that the returned pointer is never written to. If you need to mutate the contents of the string slice, use as_mut_ptr.

Examples

Basic usage:

let s = "Hello";
let ptr = s.as_ptr();

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.

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());

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);

pub unsafe fn get_unchecked<I>(&self, i: I) -> &<I as SliceIndex<str>>::Output where
    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));
}

pub unsafe fn get_unchecked_mut<I>(
    &mut self,
    i: I
) -> &mut <I as SliceIndex<str>>::Output where
    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));
}

pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str

👎 Deprecated since 1.29.0:

use get_unchecked(begin..end) instead

Creates 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 exceed end.
• begin and end must be byte positions within the string slice.
• begin and end must lie on UTF-8 sequence boundaries.

Examples

Basic usage:

let s = "Löwe 老虎 Léopard";

unsafe {
    assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21));
}

let s = "Hello, world!";

unsafe {
    assert_eq!("world", s.slice_unchecked(7, 12));
}

pub 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

Creates 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 exceed end.
• begin and end must be byte positions within the string slice.
• begin and end must lie on UTF-8 sequence boundaries.

pub fn split_at(&self, mid: usize) -> (&str, &str)

Divide one string slice into two at an index.

The argument, mid, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.

The two slices returned go from the start of the string slice to mid, and from mid to the end of the string slice.

To get mutable string slices instead, see the split_at_mut method.

Panics

Panics if mid is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice.

Examples

Basic usage:

let s = "Per Martin-Löf";

let (first, last) = s.split_at(3);

assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);

pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)

Divide one mutable string slice into two at an index.

The argument, mid, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.

The two slices returned go from the start of the string slice to mid, and from mid to the end of the string slice.

To get immutable string slices instead, see the split_at method.

Panics

Panics if mid is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice.

Examples

Basic usage:

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);

pub fn chars(&self) -> Chars<'_>

Returns an iterator over the chars of a string slice.

As a string slice consists of valid UTF-8, we can iterate through a string slice by char. This method returns such an iterator.

It’s important to remember that char represents a Unicode Scalar Value, and may not match your idea of what a ‘character’ is. Iteration over grapheme clusters may be what you actually want. This functionality is not provided by Rust’s standard library, check crates.io instead.

Examples

Basic usage:

let word = "goodbye";

let count = word.chars().count();
assert_eq!(7, count);

let mut chars = word.chars();

assert_eq!(Some('g'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('d'), chars.next());
assert_eq!(Some('b'), chars.next());
assert_eq!(Some('y'), chars.next());
assert_eq!(Some('e'), chars.next());

assert_eq!(None, chars.next());

Remember, chars may 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());

pub fn char_indices(&self) -> CharIndices<'_>

Returns an iterator over the chars of a string slice, and their positions.

As a string slice consists of valid UTF-8, we can iterate through a string slice by char. This method returns an iterator of both these chars, as well as their byte positions.

The iterator yields tuples. The position is first, the char is second.

Examples

Basic usage:

let word = "goodbye";

let count = word.char_indices().count();
assert_eq!(7, count);

let mut char_indices = word.char_indices();

assert_eq!(Some((0, 'g')), char_indices.next());
assert_eq!(Some((1, 'o')), char_indices.next());
assert_eq!(Some((2, 'o')), char_indices.next());
assert_eq!(Some((3, 'd')), char_indices.next());
assert_eq!(Some((4, 'b')), char_indices.next());
assert_eq!(Some((5, 'y')), char_indices.next());
assert_eq!(Some((6, 'e')), char_indices.next());

assert_eq!(None, char_indices.next());

Remember, chars may not match your intuition about characters:

let yes = "y̆es";

let mut char_indices = yes.char_indices();

assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
assert_eq!(Some((1, '\u{0306}')), char_indices.next());

// note the 3 here - the last character took up two bytes
assert_eq!(Some((3, 'e')), char_indices.next());
assert_eq!(Some((4, 's')), char_indices.next());

assert_eq!(None, char_indices.next());

pub fn bytes(&self) -> Bytes<'_>

An iterator over the bytes of a string slice.

As a string slice consists of a sequence of bytes, we can iterate through a string slice by byte. This method returns such an iterator.

Examples

Basic usage:

let mut bytes = "bors".bytes();

assert_eq!(Some(b'b'), bytes.next());
assert_eq!(Some(b'o'), bytes.next());
assert_eq!(Some(b'r'), bytes.next());
assert_eq!(Some(b's'), bytes.next());

assert_eq!(None, bytes.next());

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());

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());

pub fn lines(&self) -> Lines<'_>

An iterator over the lines of a string, as string slices.

Lines are ended with either a newline (\n) or a carriage return with a line feed (\r\n).

The final line ending is optional. A string that ends with a final line ending will return the same lines as an otherwise identical string without a final line ending.

Examples

Basic usage:

let text = "foo\r\nbar\n\nbaz\n";
let mut lines = text.lines();

assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
assert_eq!(Some("baz"), lines.next());

assert_eq!(None, lines.next());

The final line ending isn’t required:

let text = "foo\nbar\n\r\nbaz";
let mut lines = text.lines();

assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
assert_eq!(Some("baz"), lines.next());

assert_eq!(None, lines.next());

pub fn lines_any(&self) -> LinesAny<'_>

👎 Deprecated since 1.4.0:

use lines() instead now

An iterator over the lines of a string.

pub fn encode_utf16(&self) -> EncodeUtf16<'_>

Returns an iterator of u16 over the string encoded as UTF-16.

Examples

Basic usage:

let text = "Zażółć gęślą jaźń";

let utf8_len = text.len();
let utf16_len = text.encode_utf16().count();

assert!(utf16_len <= utf8_len);

pub fn contains<'a, P>(&'a self, pat: P) -> bool where
    P: Pattern<'a>, 

Returns true if the given pattern matches a sub-slice of this string slice.

Returns false if it does not.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Basic usage:

let bananas = "bananas";

assert!(bananas.contains("nana"));
assert!(!bananas.contains("apples"));

pub fn starts_with<'a, P>(&'a self, pat: P) -> bool where
    P: Pattern<'a>, 

Returns true if the given pattern matches a prefix of this string slice.

Returns false if it does not.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Basic usage:

let bananas = "bananas";

assert!(bananas.starts_with("bana"));
assert!(!bananas.starts_with("nana"));

pub fn ends_with<'a, P>(&'a self, pat: P) -> bool where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

Returns true if the given pattern matches a suffix of this string slice.

Returns false if it does not.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Basic usage:

let bananas = "bananas";

assert!(bananas.ends_with("anas"));
assert!(!bananas.ends_with("nana"));

pub fn find<'a, P>(&'a self, pat: P) -> Option<usize> where
    P: Pattern<'a>, 

Returns the byte index of the first character of this string slice that matches the pattern.

Returns None if the pattern doesn’t match.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Simple patterns:

let s = "Löwe 老虎 Léopard Gepardi";

assert_eq!(s.find('L'), Some(0));
assert_eq!(s.find('é'), Some(14));
assert_eq!(s.find("pard"), Some(17));

More complex patterns using point-free style and closures:

let s = "Löwe 老虎 Léopard";

assert_eq!(s.find(char::is_whitespace), Some(5));
assert_eq!(s.find(char::is_lowercase), Some(1));
assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1));
assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));

Not finding the pattern:

let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];

assert_eq!(s.find(x), None);

pub fn rfind<'a, P>(&'a self, pat: P) -> Option<usize> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

Returns the byte index for the first character of the rightmost match of the pattern in this string slice.

Returns None if the pattern doesn’t match.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Simple patterns:

let s = "Löwe 老虎 Léopard Gepardi";

assert_eq!(s.rfind('L'), Some(13));
assert_eq!(s.rfind('é'), Some(14));
assert_eq!(s.rfind("pard"), Some(24));

More complex patterns with closures:

let s = "Löwe 老虎 Léopard";

assert_eq!(s.rfind(char::is_whitespace), Some(12));
assert_eq!(s.rfind(char::is_lowercase), Some(20));

Not finding the pattern:

let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];

assert_eq!(s.rfind(x), None);

pub fn split<'a, P>(&'a self, pat: P) -> Split<'a, P> where
    P: Pattern<'a>, 

An iterator over substrings of this string slice, separated by characters matched by a pattern.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rsplit method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);

let v: Vec<&str> = "".split('X').collect();
assert_eq!(v, [""]);

let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
assert_eq!(v, ["lion", "", "tiger", "leopard"]);

let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);

let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect();
assert_eq!(v, ["abc", "def", "ghi"]);

let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);

If the pattern is a slice of chars, split on each occurrence of any of the characters:

let v: Vec<&str> = "2020-11-03 23:59".split(&['-', ' ', ':', '@'][..]).collect();
assert_eq!(v, ["2020", "11", "03", "23", "59"]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect();
assert_eq!(v, ["abc", "def", "ghi"]);

If a string contains multiple contiguous separators, you will end up with empty strings in the output:

let x = "||||a||b|c".to_string();
let d: Vec<_> = x.split('|').collect();

assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);

Contiguous separators are separated by the empty string.

let x = "(///)".to_string();
let d: Vec<_> = x.split('/').collect();

assert_eq!(d, &["(", "", "", ")"]);

Separators at the start or end of a string are neighbored by empty strings.

let d: Vec<_> = "010".split("0").collect();
assert_eq!(d, &["", "1", ""]);

When the empty string is used as a separator, it separates every character in the string, along with the beginning and end of the string.

let f: Vec<_> = "rust".split("").collect();
assert_eq!(f, &["", "r", "u", "s", "t", ""]);

Contiguous separators can lead to possibly surprising behavior when whitespace is used as the separator. This code is correct:

let x = "    a  b c".to_string();
let d: Vec<_> = x.split(' ').collect();

assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);

It does not give you:

assert_eq!(d, &["a", "b", "c"]);

Use split_whitespace for this behavior.

pub fn split_inclusive<'a, P>(&'a self, pat: P) -> SplitInclusive<'a, P> where
    P: Pattern<'a>, 

An iterator over substrings of this string slice, separated by characters matched by a pattern. Differs from the iterator produced by split in that split_inclusive leaves the matched part as the terminator of the substring.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
    .split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);

If the last element of the string is matched, that element will be considered the terminator of the preceding substring. That substring will be the last item returned by the iterator.

let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n"
    .split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);

pub fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

An iterator over substrings of the given string slice, separated by characters matched by a pattern and yielded in reverse order.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator if a forward/reverse search yields the same elements.

For iterating from the front, the split method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);

let v: Vec<&str> = "".rsplit('X').collect();
assert_eq!(v, [""]);

let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
assert_eq!(v, ["leopard", "tiger", "", "lion"]);

let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
assert_eq!(v, ["leopard", "tiger", "lion"]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "def", "abc"]);

pub fn split_terminator<'a, P>(&'a self, pat: P) -> SplitTerminator<'a, P> where
    P: Pattern<'a>, 

An iterator over substrings of the given string slice, separated by characters matched by a pattern.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Equivalent to split, except that the trailing substring is skipped if empty.

This method can be used for string data that is terminated, rather than separated by a pattern.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rsplit_terminator method can be used.

Examples

Basic usage:

let v: Vec<&str> = "A.B.".split_terminator('.').collect();
assert_eq!(v, ["A", "B"]);

let v: Vec<&str> = "A..B..".split_terminator(".").collect();
assert_eq!(v, ["A", "", "B", ""]);

pub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

An iterator over substrings of self, separated by characters matched by a pattern and yielded in reverse order.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Equivalent to split, except that the trailing substring is skipped if empty.

This method can be used for string data that is terminated, rather than separated by a pattern.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be double ended if a forward/reverse search yields the same elements.

For iterating from the front, the split_terminator method can be used.

Examples

let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
assert_eq!(v, ["B", "A"]);

let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
assert_eq!(v, ["", "B", "", "A"]);

pub fn splitn<'a, P>(&'a self, n: usize, pat: P) -> SplitN<'a, P> where
    P: Pattern<'a>, 

An iterator over substrings of the given string slice, separated by a pattern, restricted to returning at most n items.

If n substrings are returned, the last substring (the nth substring) will contain the remainder of the string.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will not be double ended, because it is not efficient to support.

If the pattern allows a reverse search, the rsplitn method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
assert_eq!(v, ["Mary", "had", "a little lambda"]);

let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
assert_eq!(v, ["lion", "", "tigerXleopard"]);

let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
assert_eq!(v, ["abcXdef"]);

let v: Vec<&str> = "".splitn(1, 'X').collect();
assert_eq!(v, [""]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["abc", "defXghi"]);

pub fn rsplitn<'a, P>(&'a self, n: usize, pat: P) -> RSplitN<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

An iterator over substrings of this string slice, separated by a pattern, starting from the end of the string, restricted to returning at most n items.

If n substrings are returned, the last substring (the nth substring) will contain the remainder of the string.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will not be double ended, because it is not efficient to support.

For splitting from the front, the splitn method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
assert_eq!(v, ["lamb", "little", "Mary had a"]);

let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
assert_eq!(v, ["leopard", "tiger", "lionX"]);

let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
assert_eq!(v, ["leopard", "lion::tiger"]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "abc1def"]);

pub fn split_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)> where
    P: Pattern<'a>, 

Splits the string on the first occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.

Examples

assert_eq!("cfg".split_once('='), None);
assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));

pub fn rsplit_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

Splits the string on the last occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.

Examples

assert_eq!("cfg".rsplit_once('='), None);
assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));

pub fn matches<'a, P>(&'a self, pat: P) -> Matches<'a, P> where
    P: Pattern<'a>, 

An iterator over the disjoint matches of a pattern within the given string slice.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rmatches method can be used.

Examples

Basic usage:

let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);

let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect();
assert_eq!(v, ["1", "2", "3"]);

pub fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

An iterator over the disjoint matches of a pattern within this string slice, yielded in reverse order.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator if a forward/reverse search yields the same elements.

For iterating from the front, the matches method can be used.

Examples

Basic usage:

let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);

let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect();
assert_eq!(v, ["3", "2", "1"]);

pub fn match_indices<'a, P>(&'a self, pat: P) -> MatchIndices<'a, P> where
    P: Pattern<'a>, 

An iterator over the disjoint matches of a pattern within this string slice as well as the index that the match starts at.

For matches of pat within self that overlap, only the indices corresponding to the first match are returned.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rmatch_indices method can be used.

Examples

Basic usage:

let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect();
assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]);

let v: Vec<_> = "1abcabc2".match_indices("abc").collect();
assert_eq!(v, [(1, "abc"), (4, "abc")]);

let v: Vec<_> = "ababa".match_indices("aba").collect();
assert_eq!(v, [(0, "aba")]); // only the first `aba`

pub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

An iterator over the disjoint matches of a pattern within self, yielded in reverse order along with the index of the match.

For matches of pat within self that overlap, only the indices corresponding to the last match are returned.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator if a forward/reverse search yields the same elements.

For iterating from the front, the match_indices method can be used.

Examples

Basic usage:

let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect();
assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]);

let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect();
assert_eq!(v, [(4, "abc"), (1, "abc")]);

let v: Vec<_> = "ababa".rmatch_indices("aba").collect();
assert_eq!(v, [(2, "aba")]); // only the last `aba`

#[must_use = "this returns the trimmed string as a slice, \ without modifying the original"]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.

Examples

Basic usage:

let s = " Hello\tworld\t";

assert_eq!("Hello\tworld", s.trim());

#[must_use = "this returns the trimmed string as a new slice, \ without modifying the original"]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.

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 = " Hello\tworld\t";
assert_eq!("Hello\tworld\t", 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());

#[must_use = "this returns the trimmed string as a new slice, \ without modifying the original"]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.

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 = " Hello\tworld\t";
assert_eq!(" 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());

pub fn trim_left(&self) -> &str

👎 Deprecated since 1.33.0:

superseded by 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());

pub fn trim_right(&self) -> &str

👎 Deprecated since 1.33.0:

superseded by 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());

#[must_use = "this returns the trimmed string as a new slice, \ without modifying the original"]pub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: DoubleEndedSearcher<'a>, 

Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.

The pattern can be a char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Simple patterns:

assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");

A more complex pattern, using a closure:

assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");

#[must_use = "this returns the trimmed string as a new slice, \ without modifying the original"]pub fn trim_start_matches<'a, P>(&'a self, pat: P) -> &'a str where
    P: Pattern<'a>, 

Returns a string slice with all prefixes that match a pattern repeatedly removed.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. start in this context means the first position of that byte string; for a left-to-right language like English or Russian, this will be left side, and for right-to-left languages like Arabic or Hebrew, this will be the right side.

Examples

Basic usage:

assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");

#[must_use = "this returns the remaining substring as a new slice, \ without modifying the original"]pub fn strip_prefix<'a, P>(&'a self, prefix: P) -> Option<&'a str> where
    P: Pattern<'a>, 

Returns a string slice with the prefix removed.

If the string starts with the pattern prefix, returns substring after the prefix, wrapped in Some. Unlike trim_start_matches, this method removes the prefix exactly once.

If the string does not start with prefix, returns None.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar"));
assert_eq!("foo:bar".strip_prefix("bar"), None);
assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));

#[must_use = "this returns the remaining substring as a new slice, \ without modifying the original"]pub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str> where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

Returns a string slice with the suffix removed.

If the string ends with the pattern suffix, returns the substring before the suffix, wrapped in Some. Unlike trim_end_matches, this method removes the suffix exactly once.

If the string does not end with suffix, returns None.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar"));
assert_eq!("bar:foo".strip_suffix("bar"), None);
assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));

#[must_use = "this returns the trimmed string as a new slice, \ without modifying the original"]pub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a str where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

Returns a string slice with all suffixes that match a pattern repeatedly removed.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. end in this context means the last position of that byte string; for a left-to-right language like English or Russian, this will be right side, and for right-to-left languages like Arabic or Hebrew, this will be the left side.

Examples

Simple patterns:

assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");

A more complex pattern, using a closure:

assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");

pub fn trim_left_matches<'a, P>(&'a self, pat: P) -> &'a str where
    P: Pattern<'a>, 

👎 Deprecated since 1.33.0:

superseded by 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 chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.

Examples

Basic usage:

assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");

pub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str where
    P: Pattern<'a>,
    <P as Pattern<'a>>::Searcher: ReverseSearcher<'a>, 

👎 Deprecated since 1.33.0:

superseded by 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 chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.

Examples

Simple patterns:

assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");

A more complex pattern, using a closure:

assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");

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());

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());

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"));

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);

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);

pub fn escape_debug(&self) -> EscapeDebug<'_>

Return an iterator that escapes each char in self with char::escape_debug.

Note: only extended grapheme codepoints that begin the string will be escaped.

Examples

As an iterator:

for c in "❤\n!".escape_debug() {
    print!("{}", c);
}
println!();

Using println! directly:

println!("{}", "❤\n!".escape_debug());

Both are equivalent to:

println!("❤\\n!");

Using to_string:

assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");

pub fn escape_default(&self) -> EscapeDefault<'_>

Return an iterator that escapes each char in self with char::escape_default.

Examples

As an iterator:

for c in "❤\n!".escape_default() {
    print!("{}", c);
}
println!();

Using println! directly:

println!("{}", "❤\n!".escape_default());

Both are equivalent to:

println!("\\u{{2764}}\\n!");

Using to_string:

assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");

pub fn escape_unicode(&self) -> EscapeUnicode<'_>

Return an iterator that escapes each char in self with char::escape_unicode.

Examples

As an iterator:

for c in "❤\n!".escape_unicode() {
    print!("{}", c);
}
println!();

Using println! directly:

println!("{}", "❤\n!".escape_unicode());

Both are equivalent to:

println!("\\u{{2764}}\\u{{a}}\\u{{21}}");

Using to_string:

assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");

#[must_use = "this returns the replaced string as a new allocation, \ without modifying the original"]pub fn replace<'a, P>(&'a self, from: P, to: &str) -> String where
    P: Pattern<'a>, 

Replaces all matches of a pattern with another string.

replace creates a new String, and copies the data from this string slice into it. While doing so, it attempts to find matches of a pattern. If it finds any, it replaces them with the replacement string slice.

Examples

Basic usage:

let s = "this is old";

assert_eq!("this is new", s.replace("old", "new"));

When the pattern doesn’t match:

let s = "this is old";
assert_eq!(s, s.replace("cookie monster", "little lamb"));

#[must_use = "this returns the replaced string as a new allocation, \ without modifying the original"]pub fn replacen<'a, P>(&'a self, pat: P, to: &str, count: usize) -> String where
    P: Pattern<'a>, 

Replaces first N matches of a pattern with another string.

replacen creates a new String, and copies the data from this string slice into it. While doing so, it attempts to find matches of a pattern. If it finds any, it replaces them with the replacement string slice at most count times.

Examples

Basic usage:

let s = "foo foo 123 foo";
assert_eq!("new new 123 foo", s.replacen("foo", "new", 2));
assert_eq!("faa fao 123 foo", s.replacen('o', "a", 3));
assert_eq!("foo foo new23 foo", s.replacen(char::is_numeric, "new", 1));

When the pattern doesn’t match:

let s = "this is old";
assert_eq!(s, s.replacen("cookie monster", "little lamb", 10));

pub fn to_lowercase(&self) -> String

Returns the lowercase equivalent of this string slice, as a new String.

‘Lowercase’ is defined according to the terms of the Unicode Derived Core Property Lowercase.

Since some characters can expand into multiple characters when changing the case, this function returns a String instead of modifying the parameter in-place.

Examples

Basic usage:

let s = "HELLO";

assert_eq!("hello", s.to_lowercase());

A tricky example, with sigma:

let sigma = "Σ";

assert_eq!("σ", sigma.to_lowercase());

// but at the end of a word, it's ς, not σ:
let odysseus = "ὈΔΥΣΣΕΎΣ";

assert_eq!("ὀδυσσεύς", odysseus.to_lowercase());

Languages without case are not changed:

let new_year = "农历新年";

assert_eq!(new_year, new_year.to_lowercase());

pub fn to_uppercase(&self) -> String

Returns the uppercase equivalent of this string slice, as a new String.

‘Uppercase’ is defined according to the terms of the Unicode Derived Core Property Uppercase.

Since some characters can expand into multiple characters when changing the case, this function returns a String instead of modifying the parameter in-place.

Examples

Basic usage:

let s = "hello";

assert_eq!("HELLO", s.to_uppercase());

Scripts without case are not changed:

let new_year = "农历新年";

assert_eq!(new_year, new_year.to_uppercase());

One character can become multiple:

let s = "tschüß";

assert_eq!("TSCHÜSS", s.to_uppercase());

pub fn repeat(&self, n: usize) -> String

Creates a new String by repeating a string n times.

Panics

This function will panic if the capacity would overflow.

Examples

Basic usage:

assert_eq!("abc".repeat(4), String::from("abcabcabcabc"));

A panic upon overflow:

// this will panic at runtime
"0123456789abcdef".repeat(usize::MAX);

pub fn to_ascii_uppercase(&self) -> String

Returns a copy of this string where each character is mapped to its ASCII upper case equivalent.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To uppercase the value in-place, use make_ascii_uppercase.

To uppercase ASCII characters in addition to non-ASCII characters, use to_uppercase.

Examples

let s = "Grüße, Jürgen ❤";

assert_eq!("GRüßE, JüRGEN ❤", s.to_ascii_uppercase());

pub fn to_ascii_lowercase(&self) -> String

Returns a copy of this string where each character is mapped to its ASCII lower case equivalent.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To lowercase the value in-place, use make_ascii_lowercase.

To lowercase ASCII characters in addition to non-ASCII characters, use to_lowercase.

Examples

let s = "Grüße, Jürgen ❤";

assert_eq!("grüße, jürgen ❤", s.to_ascii_lowercase());

Trait Implementations

impl<const N: usize> Add<&'_ str> for StaticString<N>

type Output = Self

The resulting type after applying the + operator.

fn add(self, other: &str) -> Self::Output

Performs the + operation.

impl<const N: usize> AddAssign<&'_ str> for StaticString<N>

fn add_assign(&mut self, other: &str)

Performs the += operation.

impl<const N: usize> AsMut<str> for StaticString<N>

fn as_mut(&mut self) -> &mut str

Performs the conversion.

impl<const N: usize> AsRef<[u8]> for StaticString<N>

fn as_ref(&self) -> &[u8]

Performs the conversion.

impl<const N: usize> AsRef<str> for StaticString<N>

fn as_ref(&self) -> &str

Performs the conversion.

impl<const N: usize> Borrow<str> for StaticString<N>

fn borrow(&self) -> &str

Immutably borrows from an owned value.

impl<const N: usize> BorrowMut<str> for StaticString<N>

fn borrow_mut(&mut self) -> &mut str

Mutably borrows from an owned value.

impl<const N: usize> Clone for StaticString<N>

fn clone(&self) -> Self

Returns a copy of the value.

pub fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<const N: usize> Debug for StaticString<N>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<const N: usize> Default for StaticString<N>

fn default() -> Self

Returns the “default value” for a type.

impl<const N: usize> Deref for StaticString<N>

type Target = str

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<const N: usize> DerefMut for StaticString<N>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<const N: usize> Display for StaticString<N>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<const N: usize> Eq for StaticString<N>

impl<'a, const N: usize> Extend<&'a char> for StaticString<N>

fn extend<I: IntoIterator<Item = &'a char>>(&mut self, iter: I)

Extends a collection with the contents of an iterator.

pub fn extend_one(&mut self, item: A)

🔬 This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

pub fn extend_reserve(&mut self, additional: usize)

🔬 This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<'a, const N: usize> Extend<&'a str> for StaticString<N>

fn extend<I: IntoIterator<Item = &'a str>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

pub fn extend_one(&mut self, item: A)

🔬 This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

pub fn extend_reserve(&mut self, additional: usize)

🔬 This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<const N: usize> Extend<char> for StaticString<N>

fn extend<I: IntoIterator<Item = char>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

pub fn extend_one(&mut self, item: A)

🔬 This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

pub fn extend_reserve(&mut self, additional: usize)

🔬 This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<'a, const N: usize> From<&'a str> for StaticString<N>

fn from(s: &str) -> Self

Performs the conversion.

impl<const N: usize> From<StaticString<N>> for StaticVec<u8, N>

fn from(string: StaticString<N>) -> Self

Performs the conversion.

impl<const N1: usize, const N2: usize> From<StaticString<N1>> for StaticVec<u8, N2>

default fn from(string: StaticString<N1>) -> Self

Performs the conversion.

impl<const N: usize> From<StaticVec<u8, N>> for StaticString<N>

fn from(vec: StaticVec<u8, N>) -> Self

Performs the conversion.

impl<const N1: usize, const N2: usize> From<StaticVec<u8, N1>> for StaticString<N2>

default fn from(vec: StaticVec<u8, N1>) -> Self

Performs the conversion.

impl<const N: usize> From<String> for StaticString<N>

Note: this is only available when the std crate feature is enabled.

fn from(string: String) -> Self

Performs the conversion.

impl<'a, const N: usize> FromIterator<&'a char> for StaticString<N>

fn from_iter<I: IntoIterator<Item = &'a char>>(iter: I) -> Self

Creates a value from an iterator.

impl<'a, const N: usize> FromIterator<&'a str> for StaticString<N>

fn from_iter<I: IntoIterator<Item = &'a str>>(iter: I) -> Self

Creates a value from an iterator.

impl<const N: usize> FromIterator<char> for StaticString<N>

fn from_iter<I: IntoIterator<Item = char>>(iter: I) -> Self

Creates a value from an iterator.

impl<'a, const N: usize> FromStr for StaticString<N>

type Err = ()

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl<const N: usize> Hash for StaticString<N>

fn hash<H: Hasher>(&self, hasher: &mut H)

Feeds this value into the given Hasher.

pub fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<const N: usize> Index<Range<usize>> for StaticString<N>

type Output = str

The returned type after indexing.

fn index(&self, index: Range<usize>) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<const N: usize> Index<RangeFrom<usize>> for StaticString<N>

type Output = str

The returned type after indexing.

fn index(&self, index: RangeFrom<usize>) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<const N: usize> Index<RangeFull> for StaticString<N>

type Output = str

The returned type after indexing.

fn index(&self, _index: RangeFull) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<const N: usize> Index<RangeInclusive<usize>> for StaticString<N>

type Output = str

The returned type after indexing.

fn index(&self, index: RangeInclusive<usize>) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<const N: usize> Index<RangeTo<usize>> for StaticString<N>

type Output = str

The returned type after indexing.

fn index(&self, index: RangeTo<usize>) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<const N: usize> Index<RangeToInclusive<usize>> for StaticString<N>

type Output = str

The returned type after indexing.

fn index(&self, index: RangeToInclusive<usize>) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<const N: usize> IndexMut<Range<usize>> for StaticString<N>

fn index_mut(&mut self, index: Range<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<const N: usize> IndexMut<RangeFrom<usize>> for StaticString<N>

fn index_mut(&mut self, index: RangeFrom<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<const N: usize> IndexMut<RangeFull> for StaticString<N>

fn index_mut(&mut self, _index: RangeFull) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<const N: usize> IndexMut<RangeInclusive<usize>> for StaticString<N>

fn index_mut(&mut self, index: RangeInclusive<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<const N: usize> IndexMut<RangeTo<usize>> for StaticString<N>

fn index_mut(&mut self, index: RangeTo<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<const N: usize> IndexMut<RangeToInclusive<usize>> for StaticString<N>

fn index_mut(&mut self, index: RangeToInclusive<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<const N: usize> Ord for StaticString<N>

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

#[must_use]pub fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]pub fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<const N: usize> PartialEq<&'_ str> for StaticString<N>

fn eq(&self, other: &&str) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<const N: usize> PartialEq<StaticString<N>> for StaticString<N>

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<const N: usize> PartialEq<String> for StaticString<N>

Note: this is only available when the std crate feature is enabled.

fn eq(&self, other: &String) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<const N: usize> PartialEq<str> for StaticString<N>

fn eq(&self, other: &str) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<const N: usize> PartialOrd<&'_ str> for StaticString<N>

fn partial_cmp(&self, other: &&str) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<const N: usize> PartialOrd<StaticString<N>> for StaticString<N>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<const N: usize> PartialOrd<String> for StaticString<N>

Note: this is only available when the std crate feature is enabled.

fn partial_cmp(&self, other: &String) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<const N: usize> PartialOrd<str> for StaticString<N>

fn partial_cmp(&self, other: &str) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<const N: usize> Write for StaticString<N>

fn write_str(&mut self, s: &str) -> Result

Writes a string slice into this writer, returning whether the write succeeded.

fn write_char(&mut self, c: char) -> Result

Writes a char into this writer, returning whether the write succeeded.

pub fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Glue for usage of the write! macro with implementors of this trait.