Primitive Type char

[−] Expand description

A character type.

The char type represents a single character. More specifically, since 'character' isn't a well-defined concept in Unicode, char is a 'Unicode scalar value', which is similar to, but not the same as, a 'Unicode code point'.

This documentation describes a number of methods and trait implementations on the char type. For technical reasons, there is additional, separate documentation in the std::char module as well.

Representation

char is always four bytes in size. This is a different representation than a given character would have as part of a String. For example:

let v = vec!['h', 'e', 'l', 'l', 'o'];

// five elements times four bytes for each element
assert_eq!(20, v.len() * std::mem::size_of::<char>());

let s = String::from("hello");

// five elements times one byte per element
assert_eq!(5, s.len() * std::mem::size_of::<u8>());

As always, remember that a human intuition for 'character' may not map to Unicode's definitions. For example, despite looking similar, the 'é' character is one Unicode code point while 'é' is two Unicode code points:

let mut chars = "é".chars();
// U+00e9: 'latin small letter e with acute'
assert_eq!(Some('\u{00e9}'), chars.next());
assert_eq!(None, chars.next());

let mut chars = "é".chars();
// U+0065: 'latin small letter e'
assert_eq!(Some('\u{0065}'), chars.next());
// U+0301: 'combining acute accent'
assert_eq!(Some('\u{0301}'), chars.next());
assert_eq!(None, chars.next());

This means that the contents of the first string above will fit into a char while the contents of the second string will not. Trying to create a char literal with the contents of the second string gives an error:

error: character literal may only contain one codepoint: 'é'
let c = 'é';
        ^^^^

Another implication of the 4-byte fixed size of a char is that per-char processing can end up using a lot more memory:

let s = String::from("love: ❤️");
let v: Vec<char> = s.chars().collect();

assert_eq!(12, s.len() * std::mem::size_of::<u8>());
assert_eq!(32, v.len() * std::mem::size_of::<char>());

Methods

impl char

[−]

pub fn is_digit(self, radix: u32) -> bool

[−]

Checks if a char is a digit in the given radix.

A 'radix' here is sometimes also called a 'base'. A radix of two indicates a binary number, a radix of ten, decimal, and a radix of sixteen, hexadecimal, to give some common values. Arbitrary radices are supported.

Compared to is_numeric(), this function only recognizes the characters 0-9, a-z and A-Z.

'Digit' is defined to be only the following characters:

• 0-9
• a-z
• A-Z

For a more comprehensive understanding of 'digit', see is_numeric.

Panics

Panics if given a radix larger than 36.

Examples

Basic usage:

assert!('1'.is_digit(10));
assert!('f'.is_digit(16));
assert!(!'f'.is_digit(10));

Passing a large radix, causing a panic:

use std::thread;

let result = thread::spawn(|| {
    // this panics
    '1'.is_digit(37);
}).join();

assert!(result.is_err());

pub fn to_digit(self, radix: u32) -> Option<u32>

[−]

Converts a char to a digit in the given radix.

A 'radix' here is sometimes also called a 'base'. A radix of two indicates a binary number, a radix of ten, decimal, and a radix of sixteen, hexadecimal, to give some common values. Arbitrary radices are supported.

'Digit' is defined to be only the following characters:

• 0-9
• a-z
• A-Z

Errors

Returns None if the char does not refer to a digit in the given radix.

Panics

Panics if given a radix larger than 36.

Examples

Basic usage:

assert_eq!('1'.to_digit(10), Some(1));
assert_eq!('f'.to_digit(16), Some(15));

Passing a non-digit results in failure:

assert_eq!('f'.to_digit(10), None);
assert_eq!('z'.to_digit(16), None);

Passing a large radix, causing a panic:

use std::thread;

let result = thread::spawn(|| {
    '1'.to_digit(37);
}).join();

assert!(result.is_err());

Important traits for EscapeUnicode

impl Iterator for EscapeUnicode type Item = char;

pub fn escape_unicode(self) -> EscapeUnicode

[−]

Returns an iterator that yields the hexadecimal Unicode escape of a character as chars.

This will escape characters with the Rust syntax of the form \u{NNNNNN} where NNNNNN is a hexadecimal representation.

Examples

As an iterator:

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

Using println! directly:

println!("{}", '❤'.escape_unicode());

Both are equivalent to:

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

Using to_string:

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

Important traits for EscapeDebug

impl Iterator for EscapeDebug type Item = char;

pub fn escape_debug(self) -> EscapeDebug

[−]

Returns an iterator that yields the literal escape code of a character as chars.

This will escape the characters similar to the Debug implementations of str or char.

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");

Important traits for EscapeDefault

impl Iterator for EscapeDefault type Item = char;

pub fn escape_default(self) -> EscapeDefault

[−]

Returns an iterator that yields the literal escape code of a character as chars.

The default is chosen with a bias toward producing literals that are legal in a variety of languages, including C++11 and similar C-family languages. The exact rules are:

• Tab is escaped as \t.
• Carriage return is escaped as \r.
• Line feed is escaped as \n.
• Single quote is escaped as \'.
• Double quote is escaped as \".
• Backslash is escaped as \\.
• Any character in the 'printable ASCII' range 0x20 .. 0x7e inclusive is not escaped.
• All other characters are given hexadecimal Unicode escapes; see escape_unicode.

Examples

As an iterator:

for c in '"'.escape_default() {
    print!("{}", c);
}
println!();

Using println! directly:

println!("{}", '"'.escape_default());

Both are equivalent to:

println!("\\\"");

Using to_string:

assert_eq!('"'.escape_default().to_string(), "\\\"");

pub fn len_utf8(self) -> usize

[−]

Returns the number of bytes this char would need if encoded in UTF-8.

That number of bytes is always between 1 and 4, inclusive.

Examples

Basic usage:

let len = 'A'.len_utf8();
assert_eq!(len, 1);

let len = 'ß'.len_utf8();
assert_eq!(len, 2);

let len = 'ℝ'.len_utf8();
assert_eq!(len, 3);

let len = '💣'.len_utf8();
assert_eq!(len, 4);

The &str type guarantees that its contents are UTF-8, and so we can compare the length it would take if each code point was represented as a char vs in the &str itself:

// as chars
let eastern = '東';
let capitol = '京';

// both can be represented as three bytes
assert_eq!(3, eastern.len_utf8());
assert_eq!(3, capitol.len_utf8());

// as a &str, these two are encoded in UTF-8
let tokyo = "東京";

let len = eastern.len_utf8() + capitol.len_utf8();

// we can see that they take six bytes total...
assert_eq!(6, tokyo.len());

// ... just like the &str
assert_eq!(len, tokyo.len());

pub fn len_utf16(self) -> usize

[−]

Returns the number of 16-bit code units this char would need if encoded in UTF-16.

See the documentation for len_utf8 for more explanation of this concept. This function is a mirror, but for UTF-16 instead of UTF-8.

Examples

Basic usage:

let n = 'ß'.len_utf16();
assert_eq!(n, 1);

let len = '💣'.len_utf16();
assert_eq!(len, 2);

pub fn encode_utf8(self, dst: &mut [u8]) -> &mut str

[−]

Encodes this character as UTF-8 into the provided byte buffer, and then returns the subslice of the buffer that contains the encoded character.

Panics

Panics if the buffer is not large enough. A buffer of length four is large enough to encode any char.

Examples

In both of these examples, 'ß' takes two bytes to encode.

let mut b = [0; 2];

let result = 'ß'.encode_utf8(&mut b);

assert_eq!(result, "ß");

assert_eq!(result.len(), 2);

A buffer that's too small:

use std::thread;

let result = thread::spawn(|| {
    let mut b = [0; 1];

    // this panics
   'ß'.encode_utf8(&mut b);
}).join();

assert!(result.is_err());

Important traits for &'a [u8]

impl<'a> Read for &'a [u8]impl<'a> Write for &'a mut [u8]

pub fn encode_utf16(self, dst: &mut [u16]) -> &mut [u16]

[−]

Encodes this character as UTF-16 into the provided u16 buffer, and then returns the subslice of the buffer that contains the encoded character.

Panics

Panics if the buffer is not large enough. A buffer of length 2 is large enough to encode any char.

Examples

In both of these examples, '𝕊' takes two u16s to encode.

let mut b = [0; 2];

let result = '𝕊'.encode_utf16(&mut b);

assert_eq!(result.len(), 2);

A buffer that's too small:

use std::thread;

let result = thread::spawn(|| {
    let mut b = [0; 1];

    // this panics
    '𝕊'.encode_utf16(&mut b);
}).join();

assert!(result.is_err());

pub fn is_alphabetic(self) -> bool

[−]

Returns true if this char is an alphabetic code point, and false if not.

Examples

Basic usage:

assert!('a'.is_alphabetic());
assert!('京'.is_alphabetic());

let c = '💝';
// love is many things, but it is not alphabetic
assert!(!c.is_alphabetic());

pub fn is_xid_start(self) -> bool

[−]

🔬 This is a nightly-only experimental API. (rustc_private #27812)

mainly needed for compiler internals

Returns true if this char satisfies the 'XID_Start' Unicode property, and false otherwise.

'XID_Start' is a Unicode Derived Property specified in UAX #31, mostly similar to ID_Start but modified for closure under NFKx.

pub fn is_xid_continue(self) -> bool

[−]

🔬 This is a nightly-only experimental API. (rustc_private #27812)

mainly needed for compiler internals

Returns true if this char satisfies the 'XID_Continue' Unicode property, and false otherwise.

'XID_Continue' is a Unicode Derived Property specified in UAX #31, mostly similar to 'ID_Continue' but modified for closure under NFKx.

pub fn is_lowercase(self) -> bool

[−]

Returns true if this char is lowercase, and false otherwise.

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

Examples

Basic usage:

assert!('a'.is_lowercase());
assert!('δ'.is_lowercase());
assert!(!'A'.is_lowercase());
assert!(!'Δ'.is_lowercase());

// The various Chinese scripts do not have case, and so:
assert!(!'中'.is_lowercase());

pub fn is_uppercase(self) -> bool

[−]

Returns true if this char is uppercase, and false otherwise.

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

Examples

Basic usage:

assert!(!'a'.is_uppercase());
assert!(!'δ'.is_uppercase());
assert!('A'.is_uppercase());
assert!('Δ'.is_uppercase());

// The various Chinese scripts do not have case, and so:
assert!(!'中'.is_uppercase());

pub fn is_whitespace(self) -> bool

[−]

Returns true if this char is whitespace, and false otherwise.

'Whitespace' is defined according to the terms of the Unicode Derived Core Property White_Space.

Examples

Basic usage:

assert!(' '.is_whitespace());

// a non-breaking space
assert!('\u{A0}'.is_whitespace());

assert!(!'越'.is_whitespace());

pub fn is_alphanumeric(self) -> bool

[−]

Returns true if this char is alphanumeric, and false otherwise.

'Alphanumeric'-ness is defined in terms of the Unicode General Categories 'Nd', 'Nl', 'No' and the Derived Core Property 'Alphabetic'.

Examples

Basic usage:

assert!('٣'.is_alphanumeric());
assert!('7'.is_alphanumeric());
assert!('৬'.is_alphanumeric());
assert!('K'.is_alphanumeric());
assert!('و'.is_alphanumeric());
assert!('藏'.is_alphanumeric());
assert!(!'¾'.is_alphanumeric());
assert!(!'①'.is_alphanumeric());

pub fn is_control(self) -> bool

[−]

Returns true if this char is a control code point, and false otherwise.

'Control code point' is defined in terms of the Unicode General Category Cc.

Examples

Basic usage:

// U+009C, STRING TERMINATOR
assert!('œ'.is_control());
assert!(!'q'.is_control());

pub fn is_numeric(self) -> bool

[−]

Returns true if this char is numeric, and false otherwise.

'Numeric'-ness is defined in terms of the Unicode General Categories 'Nd', 'Nl', 'No'.

Examples

Basic usage:

assert!('٣'.is_numeric());
assert!('7'.is_numeric());
assert!('৬'.is_numeric());
assert!(!'K'.is_numeric());
assert!(!'و'.is_numeric());
assert!(!'藏'.is_numeric());
assert!(!'¾'.is_numeric());
assert!(!'①'.is_numeric());

Important traits for ToLowercase

impl Iterator for ToLowercase type Item = char;

pub fn to_lowercase(self) -> ToLowercase

[−]

Returns an iterator that yields the lowercase equivalent of a char as one or more chars.

If a character does not have a lowercase equivalent, the same character will be returned back by the iterator.

This performs complex unconditional mappings with no tailoring: it maps one Unicode character to its lowercase equivalent according to the Unicode database and the additional complex mappings SpecialCasing.txt. Conditional mappings (based on context or language) are not considered here.

For a full reference, see here.

Examples

As an iterator:

for c in 'İ'.to_lowercase() {
    print!("{}", c);
}
println!();

Using println! directly:

println!("{}", 'İ'.to_lowercase());

Both are equivalent to:

println!("i\u{307}");

Using to_string:

assert_eq!('C'.to_lowercase().to_string(), "c");

// Sometimes the result is more than one character:
assert_eq!('İ'.to_lowercase().to_string(), "i\u{307}");

// Characters that do not have both uppercase and lowercase
// convert into themselves.
assert_eq!('山'.to_lowercase().to_string(), "山");

Important traits for ToUppercase

impl Iterator for ToUppercase type Item = char;

pub fn to_uppercase(self) -> ToUppercase

[−]

Returns an iterator that yields the uppercase equivalent of a char as one or more chars.

If a character does not have an uppercase equivalent, the same character will be returned back by the iterator.

This performs complex unconditional mappings with no tailoring: it maps one Unicode character to its uppercase equivalent according to the Unicode database and the additional complex mappings SpecialCasing.txt. Conditional mappings (based on context or language) are not considered here.

For a full reference, see here.

Examples

As an iterator:

for c in 'ß'.to_uppercase() {
    print!("{}", c);
}
println!();

Using println! directly:

println!("{}", 'ß'.to_uppercase());

Both are equivalent to:

println!("SS");

Using to_string:

assert_eq!('c'.to_uppercase().to_string(), "C");

// Sometimes the result is more than one character:
assert_eq!('ß'.to_uppercase().to_string(), "SS");

// Characters that do not have both uppercase and lowercase
// convert into themselves.
assert_eq!('山'.to_uppercase().to_string(), "山");

Note on locale

In Turkish, the equivalent of 'i' in Latin has five forms instead of two:

• 'Dotless': I / ı, sometimes written ï
• 'Dotted': İ / i

Note that the lowercase dotted 'i' is the same as the Latin. Therefore:

let upper_i = 'i'.to_uppercase().to_string();

The value of upper_i here relies on the language of the text: if we're in en-US, it should be "I", but if we're in tr_TR, it should be "İ". to_uppercase() does not take this into account, and so:

let upper_i = 'i'.to_uppercase().to_string();

assert_eq!(upper_i, "I");

holds across languages.

pub fn is_ascii(&self) -> bool

[−]

Checks if the value is within the ASCII range.

Examples

let ascii = 'a';
let non_ascii = '❤';

assert!(ascii.is_ascii());
assert!(!non_ascii.is_ascii());

pub fn to_ascii_uppercase(&self) -> char

[−]

Makes a copy of the value in 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 ascii = 'a';
let non_ascii = '❤';

assert_eq!('A', ascii.to_ascii_uppercase());
assert_eq!('❤', non_ascii.to_ascii_uppercase());

pub fn to_ascii_lowercase(&self) -> char

[−]

Makes a copy of the value in 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 ascii = 'A';
let non_ascii = '❤';

assert_eq!('a', ascii.to_ascii_lowercase());
assert_eq!('❤', non_ascii.to_ascii_lowercase());

pub fn eq_ignore_ascii_case(&self, other: &char) -> bool

[−]

Checks that two values are an ASCII case-insensitive match.

Equivalent to to_ascii_lowercase(a) == to_ascii_lowercase(b).

Examples

let upper_a = 'A';
let lower_a = 'a';
let lower_z = 'z';

assert!(upper_a.eq_ignore_ascii_case(&lower_a));
assert!(upper_a.eq_ignore_ascii_case(&upper_a));
assert!(!upper_a.eq_ignore_ascii_case(&lower_z));

pub fn make_ascii_uppercase(&mut self)

[−]

Converts this type 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 ascii = 'a';

ascii.make_ascii_uppercase();

assert_eq!('A', ascii);

pub fn make_ascii_lowercase(&mut self)

[−]

Converts this type 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 ascii = 'A';

ascii.make_ascii_lowercase();

assert_eq!('a', ascii);

pub fn is_ascii_alphabetic(&self) -> bool

[−]

Checks if the value is an ASCII alphabetic character:

• U+0041 'A' ... U+005A 'Z', or
• U+0061 'a' ... U+007A 'z'.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(uppercase_a.is_ascii_alphabetic());
assert!(uppercase_g.is_ascii_alphabetic());
assert!(a.is_ascii_alphabetic());
assert!(g.is_ascii_alphabetic());
assert!(!zero.is_ascii_alphabetic());
assert!(!percent.is_ascii_alphabetic());
assert!(!space.is_ascii_alphabetic());
assert!(!lf.is_ascii_alphabetic());
assert!(!esc.is_ascii_alphabetic());

pub fn is_ascii_uppercase(&self) -> bool

[−]

Checks if the value is an ASCII uppercase character: U+0041 'A' ... U+005A 'Z'.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(uppercase_a.is_ascii_uppercase());
assert!(uppercase_g.is_ascii_uppercase());
assert!(!a.is_ascii_uppercase());
assert!(!g.is_ascii_uppercase());
assert!(!zero.is_ascii_uppercase());
assert!(!percent.is_ascii_uppercase());
assert!(!space.is_ascii_uppercase());
assert!(!lf.is_ascii_uppercase());
assert!(!esc.is_ascii_uppercase());

pub fn is_ascii_lowercase(&self) -> bool

[−]

Checks if the value is an ASCII lowercase character: U+0061 'a' ... U+007A 'z'.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(!uppercase_a.is_ascii_lowercase());
assert!(!uppercase_g.is_ascii_lowercase());
assert!(a.is_ascii_lowercase());
assert!(g.is_ascii_lowercase());
assert!(!zero.is_ascii_lowercase());
assert!(!percent.is_ascii_lowercase());
assert!(!space.is_ascii_lowercase());
assert!(!lf.is_ascii_lowercase());
assert!(!esc.is_ascii_lowercase());

pub fn is_ascii_alphanumeric(&self) -> bool

[−]

Checks if the value is an ASCII alphanumeric character:

• U+0041 'A' ... U+005A 'Z', or
• U+0061 'a' ... U+007A 'z', or
• U+0030 '0' ... U+0039 '9'.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(uppercase_a.is_ascii_alphanumeric());
assert!(uppercase_g.is_ascii_alphanumeric());
assert!(a.is_ascii_alphanumeric());
assert!(g.is_ascii_alphanumeric());
assert!(zero.is_ascii_alphanumeric());
assert!(!percent.is_ascii_alphanumeric());
assert!(!space.is_ascii_alphanumeric());
assert!(!lf.is_ascii_alphanumeric());
assert!(!esc.is_ascii_alphanumeric());

pub fn is_ascii_digit(&self) -> bool

[−]

Checks if the value is an ASCII decimal digit: U+0030 '0' ... U+0039 '9'.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(!uppercase_a.is_ascii_digit());
assert!(!uppercase_g.is_ascii_digit());
assert!(!a.is_ascii_digit());
assert!(!g.is_ascii_digit());
assert!(zero.is_ascii_digit());
assert!(!percent.is_ascii_digit());
assert!(!space.is_ascii_digit());
assert!(!lf.is_ascii_digit());
assert!(!esc.is_ascii_digit());

pub fn is_ascii_hexdigit(&self) -> bool

[−]

Checks if the value is an ASCII hexadecimal digit:

• U+0030 '0' ... U+0039 '9', or
• U+0041 'A' ... U+0046 'F', or
• U+0061 'a' ... U+0066 'f'.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(uppercase_a.is_ascii_hexdigit());
assert!(!uppercase_g.is_ascii_hexdigit());
assert!(a.is_ascii_hexdigit());
assert!(!g.is_ascii_hexdigit());
assert!(zero.is_ascii_hexdigit());
assert!(!percent.is_ascii_hexdigit());
assert!(!space.is_ascii_hexdigit());
assert!(!lf.is_ascii_hexdigit());
assert!(!esc.is_ascii_hexdigit());

pub fn is_ascii_punctuation(&self) -> bool

[−]

Checks if the value is an ASCII punctuation character:

• U+0021 ... U+002F ! " # $ % & ' ( ) * + , - . /, or
• U+003A ... U+0040 : ; < = > ? @, or
• U+005B ... U+0060 [ \ ] ^ _ `, or
• U+007B ... U+007E { | } ~

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(!uppercase_a.is_ascii_punctuation());
assert!(!uppercase_g.is_ascii_punctuation());
assert!(!a.is_ascii_punctuation());
assert!(!g.is_ascii_punctuation());
assert!(!zero.is_ascii_punctuation());
assert!(percent.is_ascii_punctuation());
assert!(!space.is_ascii_punctuation());
assert!(!lf.is_ascii_punctuation());
assert!(!esc.is_ascii_punctuation());

pub fn is_ascii_graphic(&self) -> bool

[−]

Checks if the value is an ASCII graphic character: U+0021 '!' ... U+007E '~'.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(uppercase_a.is_ascii_graphic());
assert!(uppercase_g.is_ascii_graphic());
assert!(a.is_ascii_graphic());
assert!(g.is_ascii_graphic());
assert!(zero.is_ascii_graphic());
assert!(percent.is_ascii_graphic());
assert!(!space.is_ascii_graphic());
assert!(!lf.is_ascii_graphic());
assert!(!esc.is_ascii_graphic());

pub fn is_ascii_whitespace(&self) -> bool

[−]

Checks if the value is an ASCII whitespace character: U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED, U+000C FORM FEED, or U+000D CARRIAGE RETURN.

Rust uses the WhatWG Infra Standard's definition of ASCII whitespace. There are several other definitions in wide use. For instance, the POSIX locale includes U+000B VERTICAL TAB as well as all the above characters, but—from the very same specification—the default rule for "field splitting" in the Bourne shell considers only SPACE, HORIZONTAL TAB, and LINE FEED as whitespace.

If you are writing a program that will process an existing file format, check what that format's definition of whitespace is before using this function.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(!uppercase_a.is_ascii_whitespace());
assert!(!uppercase_g.is_ascii_whitespace());
assert!(!a.is_ascii_whitespace());
assert!(!g.is_ascii_whitespace());
assert!(!zero.is_ascii_whitespace());
assert!(!percent.is_ascii_whitespace());
assert!(space.is_ascii_whitespace());
assert!(lf.is_ascii_whitespace());
assert!(!esc.is_ascii_whitespace());

pub fn is_ascii_control(&self) -> bool

[−]

Checks if the value is an ASCII control character: U+0000 NUL ... U+001F UNIT SEPARATOR, or U+007F DELETE. Note that most ASCII whitespace characters are control characters, but SPACE is not.

Examples

#![feature(ascii_ctype)]

let uppercase_a = 'A';
let uppercase_g = 'G';
let a = 'a';
let g = 'g';
let zero = '0';
let percent = '%';
let space = ' ';
let lf = '\n';
let esc: char = 0x1b_u8.into();

assert!(!uppercase_a.is_ascii_control());
assert!(!uppercase_g.is_ascii_control());
assert!(!a.is_ascii_control());
assert!(!g.is_ascii_control());
assert!(!zero.is_ascii_control());
assert!(!percent.is_ascii_control());
assert!(!space.is_ascii_control());
assert!(lf.is_ascii_control());
assert!(esc.is_ascii_control());

Trait Implementations

impl Debug for char

[+]

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

[−]

Formats the value using the given formatter.

impl TryFrom<u32> for char

[+]

type Error = CharTryFromError

🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

fn try_from(i: u32) -> Result<char, <char as TryFrom<u32>>::Error>

[−]

🔬 This is a nightly-only experimental API. (try_from #33417)

Performs the conversion.

impl Ord for char

[+]

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

[−]

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

[−]

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

[−]

Compares and returns the minimum of two values.

impl Hash for char

[+]

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

[−]

Feeds this value into the given [Hasher].

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

[−]

Feeds a slice of this type into the given [Hasher].

impl PartialEq<char> for char

[+]

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

[−]

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

fn ne(&self, other: &char) -> bool

[−]

This method tests for !=.

impl<'a> Pattern<'a> for char

[+]

Searches for chars that are equal to a given char

type Searcher = CharSearcher<'a>

🔬 This is a nightly-only experimental API. (pattern #27721)

API not fully fleshed out and ready to be stabilized

Associated searcher for this pattern

fn into_searcher(self, haystack: &'a str) -> <char as Pattern<'a>>::Searcher

[−]

🔬 This is a nightly-only experimental API. (pattern #27721)

API not fully fleshed out and ready to be stabilized

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

fn is_contained_in(self, haystack: &'a str) -> bool

[−]

🔬 This is a nightly-only experimental API. (pattern #27721)

API not fully fleshed out and ready to be stabilized

Checks whether the pattern matches anywhere in the haystack

fn is_prefix_of(self, haystack: &'a str) -> bool

[−]

🔬 This is a nightly-only experimental API. (pattern #27721)

API not fully fleshed out and ready to be stabilized

Checks whether the pattern matches at the front of the haystack

fn is_suffix_of(self, haystack: &'a str) -> bool where     <char as Pattern<'a>>::Searcher: ReverseSearcher<'a>,

[−]

🔬 This is a nightly-only experimental API. (pattern #27721)

API not fully fleshed out and ready to be stabilized

Checks whether the pattern matches at the back of the haystack

impl From<u8> for char

[+]

Maps a byte in 0x00...0xFF to a char whose code point has the same value, in U+0000 to U+00FF.

Unicode is designed such that this effectively decodes bytes with the character encoding that IANA calls ISO-8859-1. This encoding is compatible with ASCII.

Note that this is different from ISO/IEC 8859-1 a.k.a. ISO 8859-1 (with one less hyphen), which leaves some "blanks", byte values that are not assigned to any character. ISO-8859-1 (the IANA one) assigns them to the C0 and C1 control codes.

Note that this is also different from Windows-1252 a.k.a. code page 1252, which is a superset ISO/IEC 8859-1 that assigns some (not all!) blanks to punctuation and various Latin characters.

To confuse things further, on the Web ascii, iso-8859-1, and windows-1252 are all aliases for a superset of Windows-1252 that fills the remaining blanks with corresponding C0 and C1 control codes.

fn from(i: u8) -> char

[−]

Performs the conversion.

impl FromStr for char

[+]

type Err = ParseCharError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<char, <char as FromStr>::Err>

[−]

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

impl Display for char

[+]

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

[−]

Formats the value using the given formatter.

impl Default for char

[+]

fn default() -> char

[−]

Returns the default value of \x00

impl PartialOrd<char> for char

[+]

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

[−]

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

fn lt(&self, other: &char) -> bool

[−]

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

fn le(&self, other: &char) -> bool

[−]

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

fn ge(&self, other: &char) -> bool

[−]

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

fn gt(&self, other: &char) -> bool

[−]

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

impl Eq for char

impl AsciiExt for char

[+]

type Owned = char

Deprecated since 1.26.0

: use inherent methods instead

Container type for copied ASCII characters.

fn is_ascii(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

Checks if the value is within the ASCII range.

fn to_ascii_uppercase(&self) -> Self::Owned

[−]

Deprecated since 1.26.0

: use inherent methods instead

Makes a copy of the value in its ASCII upper case equivalent.

fn to_ascii_lowercase(&self) -> Self::Owned

[−]

Deprecated since 1.26.0

: use inherent methods instead

Makes a copy of the value in its ASCII lower case equivalent.

fn eq_ignore_ascii_case(&self, o: &Self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

Checks that two values are an ASCII case-insensitive match.

fn make_ascii_uppercase(&mut self)

[−]

Deprecated since 1.26.0

: use inherent methods instead

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

fn make_ascii_lowercase(&mut self)

[−]

Deprecated since 1.26.0

: use inherent methods instead

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

fn is_ascii_alphabetic(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII alphabetic character: U+0041 'A' ... U+005A 'Z' or U+0061 'a' ... U+007A 'z'. For strings, true if all characters in the string are ASCII alphabetic.

fn is_ascii_uppercase(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII uppercase character: U+0041 'A' ... U+005A 'Z'. For strings, true if all characters in the string are ASCII uppercase.

fn is_ascii_lowercase(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII lowercase character: U+0061 'a' ... U+007A 'z'. For strings, true if all characters in the string are ASCII lowercase.

fn is_ascii_alphanumeric(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII alphanumeric character: U+0041 'A' ... U+005A 'Z', U+0061 'a' ... U+007A 'z', or U+0030 '0' ... U+0039 '9'. For strings, true if all characters in the string are ASCII alphanumeric.

fn is_ascii_digit(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII decimal digit: U+0030 '0' ... U+0039 '9'. For strings, true if all characters in the string are ASCII digits.

fn is_ascii_hexdigit(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII hexadecimal digit: U+0030 '0' ... U+0039 '9', U+0041 'A' ... U+0046 'F', or U+0061 'a' ... U+0066 'f'. For strings, true if all characters in the string are ASCII hex digits.

fn is_ascii_punctuation(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII punctuation character:

fn is_ascii_graphic(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII graphic character: U+0021 '!' ... U+007E '~'. For strings, true if all characters in the string are ASCII graphic characters.

fn is_ascii_whitespace(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII whitespace character: U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED, U+000C FORM FEED, or U+000D CARRIAGE RETURN. For strings, true if all characters in the string are ASCII whitespace.

fn is_ascii_control(&self) -> bool

[−]

Deprecated since 1.26.0

: use inherent methods instead

🔬 This is a nightly-only experimental API. (ascii_ctype #39658)

Checks if the value is an ASCII control character: U+0000 NUL ... U+001F UNIT SEPARATOR, or U+007F DELETE. Note that most ASCII whitespace characters are control characters, but SPACE is not.