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);

let len = "ƒoo".len(); // fancy f!
assert_eq!(4, len);

Returns true if this slice has a length of zero bytes.

Examples

Basic usage:

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

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

Checks that index-th byte lies at the start and/or end of a UTF-8 code point sequence.

The start and end of the string (when index == self.len()) are considered to be boundaries.

Returns false if index is greater than self.len().

Examples

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));

Converts a string slice to a byte slice.

Examples

Basic usage:

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

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.

Examples

Basic usage:

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

Creates a string slice from another string slice, bypassing safety checks.

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 come before 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));
}

Creates a string slice from another string slice, bypassing safety checks.

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

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 beyond 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);

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 beyond 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);

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

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.

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 human 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());

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 human intuition about characters:

let y = "y̆";

let mut char_indices = y.char_indices();

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

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

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());

Split 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.

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());

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.

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());

An iterator over the lines of a string.

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

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

Returns false if it does not.

Examples

Basic usage:

let bananas = "bananas";

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

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

Returns false if it does not.

Examples

Basic usage:

let bananas = "bananas";

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

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

Returns false if it does not.

Examples

Basic usage:

let bananas = "bananas";

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

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, or a closure that determines if a character matches.

Examples

Simple patterns:

let s = "Löwe 老虎 Léopard";

assert_eq!(s.find('L'), Some(0));
assert_eq!(s.find('é'), Some(14));
assert_eq!(s.find("Léopard"), Some(13));

More complex patterns with closures:

let s = "Löwe 老虎 Léopard";

assert_eq!(s.find(char::is_whitespace), Some(5));
assert_eq!(s.find(char::is_lowercase), Some(1));

Not finding the pattern:

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

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

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

Returns None if the pattern doesn't match.

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

Examples

Simple patterns:

let s = "Löwe 老虎 Léopard";

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

More complex patterns with closures:

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);

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

The pattern can be a &str, char, or a closure that determines the split.

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, eg, 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"]);

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.

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, or a closure that determines the split.

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"]);

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

The pattern can be a &str, char, or a closure that determines the split.

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, eg, 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", ""]);

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

The pattern can be a simple &str, char, or a closure that determines the split. Additional libraries might provide more complex patterns like regular expressions.

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

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

Iterator behavior

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

For iterating from the front, 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"]);

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, or a closure that determines the split.

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"]);

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, or a closure that determines the split.

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"]);

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

The pattern can be a &str, char, or a 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, eg, 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"]);

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

The pattern can be a &str, char, or a 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"]);

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, or a 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, eg, 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`

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, or a 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`

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());

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());

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());

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

The pattern can be a char or a 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");

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

The pattern can be a &str, char, or a 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");

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

The pattern can be a &str, char, or a 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_left_matches(|c| c == '1' || c == 'X'), "fooX");

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 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.

Example

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());

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"));

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 N 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));

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.

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());

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.

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());

Escapes each char in s with char::escape_debug.

Escapes each char in s with char::escape_default.

Escapes each char in s with char::escape_unicode.

Converts a Box<str> into a String without copying or allocating.

Examples

Basic usage:

let string = String::from("birthday gift");
let boxed_str = string.clone().into_boxed_str();

assert_eq!(boxed_str.into_string(), string);

Create a String by repeating a string n times.

Examples

Basic usage:

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

Converts the given value to a String. Read more

Creates owned data from borrowed data, usually by cloning. Read more

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

This method tests for !=.

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

This method tests for !=.

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

This method tests for !=.

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

This method tests for !=.

The returned type after indexing

The method for the indexing (container[index]) operation

The returned type after indexing

The method for the indexing (container[index]) operation

The returned type after indexing

The method for the indexing (container[index]) operation

The returned type after indexing

The method for the indexing (container[index]) operation

The returned type after indexing

The method for the indexing (container[index]) operation

The returned type after indexing

The method for the indexing (container[index]) operation

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

This method tests for !=.

Creates an empty str

Formats the value using the given formatter.

Associated searcher for this pattern

Constructs the associated searcher from self and the haystack to search in. Read more

Checks whether the pattern matches at the front of the haystack

Checks whether the pattern matches at the back of the haystack

Checks whether the pattern matches anywhere in the haystack

Performs the conversion.

Performs the conversion.

Formats the value using the given formatter.

This method returns an Ordering between self and other. Read more

Feeds this value into the state given, updating the hasher as necessary.

Feeds a slice of this type into the state provided.

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

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

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

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

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

The method for the mutable indexing (container[index]) operation

The method for the mutable indexing (container[index]) operation

The method for the mutable indexing (container[index]) operation

The method for the mutable indexing (container[index]) operation

The method for the mutable indexing (container[index]) operation

The method for the mutable indexing (container[index]) operation

Container type for copied ASCII characters.

Checks if the value is within the ASCII range. Read more

Makes a copy of the string in ASCII upper case. Read more

Makes a copy of the string in ASCII lower case. Read more

Checks that two strings are an ASCII case-insensitive match. Read more

Converts this type to its ASCII upper case equivalent in-place. Read more

Converts this type to its ASCII lower case equivalent in-place. Read more

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

This method tests for !=.

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

This method tests for !=.

Performs the conversion.

Returned iterator over socket addresses which this type may correspond to. Read more

Converts this object to an iterator of resolved SocketAddrs. Read more

Performs the conversion.