Returns true if self's codepoint is not equal to other's codepoint.

Concatenates this char and string.

'f' + "oo" # => "foo"

Returns a char that has this char's codepoint plus other.

'a' + 1 # => 'b'
'a' + 2 # => 'c'

Returns the difference of the codepoint values of this char and other.

'a' - 'a' # => 0
'b' - 'a' # => 1
'c' - 'a' # => 2

Returns a char that has this char's codepoint minus other.

'c' - 1 # => 'b'
'c' - 2 # => 'a'

Returns true if self's codepoint is less than other's codepoint.

Returns true if self's codepoint is less than or equal to other's codepoint.

The comparison operator.

Returns the difference of the codepoint values of self and other. The result is either negative, 0 or positive based on whether other's codepoint is less, equal, or greater than self's codepoint.

'a' <=> 'c' # => -2
'z' <=> 'z' # => 0
'c' <=> 'a' # => 2

Returns true if self's codepoint is equal to other's codepoint.

Returns true if the codepoint is equal to byte ignoring the type.

'c'.ord       # => 99
'c' === 99_u8 # => true
'c' === 99    # => true
'z' === 99    # => false

Returns true if self's codepoint is greater than other's codepoint.

Returns true if self's codepoint is greater than or equal to other's codepoint.

Returns true if this char is a letter or a number according to unicode.

'c'.alphanumeric? # => true
'8'.alphanumeric? # => true
'.'.alphanumeric? # => false

Returns true if this char is an ASCII character (codepoint is in (0..127))

Returns true if this char is an ASCII letter or number ('0' to '9', 'a' to 'z', 'A' to 'Z').

'c'.ascii_alphanumeric? # => true
'8'.ascii_alphanumeric? # => true
'.'.ascii_alphanumeric? # => false

Returns true if this char is an ASCII control character.

This includes the C0 control codes (U+0000 through U+001F) and the Delete character (U+007F).

('\u0000'..'\u0019').each do |char|
  char.control? # => true
end

('\u007F'..'\u009F').each do |char|
  char.control? # => true
end

Returns true if this char is an ASCII letter ('a' to 'z', 'A' to 'Z').

'c'.ascii_letter? # => true
'á'.ascii_letter? # => false
'8'.ascii_letter? # => false

Returns true if this char is a lowercase ASCII letter.

'c'.ascii_lowercase? # => true
'ç'.lowercase?       # => true
'G'.ascii_lowercase? # => false
'.'.ascii_lowercase? # => false

Returns true if this char is an ASCII number in specified base.

Base can be from 0 to 36 with digits from '0' to '9' and 'a' to 'z' or 'A' to 'Z'.

'4'.ascii_number?     # => true
'z'.ascii_number?     # => false
'z'.ascii_number?(36) # => true

Returns true if this char is an ASCII uppercase letter.

'H'.ascii_uppercase? # => true
'Á'.ascii_uppercase? # => false
'c'.ascii_uppercase? # => false
'.'.ascii_uppercase? # => false

Returns true if this char is an ASCII whitespace.

' '.ascii_whitespace?  # => true
'\t'.ascii_whitespace? # => true
'b'.ascii_whitespace?  # => false

Returns this char bytes as encoded by UTF-8, as an Array(UInt8).

'a'.bytes # => [97]
'あ'.bytes # => [227, 129, 130]

Returns the number of UTF-8 bytes in this char.

'a'.bytesize # => 1
'好'.bytesize # => 3

Returns true if this char is a control character according to unicode.

Returns the downcase equivalent of this char.

Note that this only works for characters whose downcase equivalent yields a single codepoint. There are a few characters, like 'İ', than when downcased result in multiple characters (in this case: 'I' and the dot mark).

For a more correct method see the method that receives a block.

'Z'.downcase # => 'z'
'x'.downcase # => 'x'
'.'.downcase # => '.'

Yields each char for the downcase equivalent of this char.

This method takes into account the possibility that an downcase version of a char might result in multiple chars, like for 'İ', which results in 'i' and a dot mark.

Returns a representation of self as an ASCII-compatible Crystal char literal, wrapped in single quotes.

Non-printable characters (see #printable?) and non-ASCII characters (codepoints larger U+007F) are escaped.

'a'.dump      # => "'a'"
'\t'.dump     # => "'\\t'"
'あ'.dump      # => "'\\u3042'"
'\u0012'.dump # => "'\\u0012'"
'😀'.dump      # => "'\\u{1F600}'"

See #unicode_escape for the format used to escape characters without a special escape sequence.

• #inspect only escapes non-printable characters.

Returns a representation of self as an ASCII-compatible Crystal char literal, wrapped in single quotes.

Non-printable characters (see #printable?) and non-ASCII characters (codepoints larger U+007F) are escaped.

'a'.dump      # => "'a'"
'\t'.dump     # => "'\\t'"
'あ'.dump      # => "'\\u3042'"
'\u0012'.dump # => "'\\u0012'"
'😀'.dump      # => "'\\u{1F600}'"

See #unicode_escape for the format used to escape characters without a special escape sequence.

• #inspect only escapes non-printable characters.

Yields each of the bytes of this char as encoded by UTF-8.

puts "'a'"
'a'.each_byte do |byte|
  puts byte
end
puts

puts "'あ'"
'あ'.each_byte do |byte|
  puts byte
end

Output:

'a'
97

'あ'
227
129
130

See Object#hash(hasher)

Returns true if this char is an ASCII hex digit ('0' to '9', 'a' to 'f', 'A' to 'F').

'5'.hex? # => true
'a'.hex? # => true
'F'.hex? # => true
'g'.hex? # => false

Returns true if this char is matched by the given sets.

Each parameter defines a set, the character is matched against the intersection of those, in other words it needs to match all sets.

If a set starts with a ^, it is negated. The sequence c1-c2 means all characters between and including c1 and c2 and is known as a range.

The backslash character \ can be used to escape ^ or - and is otherwise ignored unless it appears at the end of a range or set.

'l'.in_set? "lo"          # => true
'l'.in_set? "lo", "o"     # => false
'l'.in_set? "hello", "^l" # => false
'l'.in_set? "j-m"         # => true

'^'.in_set? "\\^aeiou" # => true
'-'.in_set? "a\\-eo"   # => true

'\\'.in_set? "\\"    # => true
'\\'.in_set? "\\A"   # => false
'\\'.in_set? "X-\\w" # => true

Returns a representation of self as a Crystal char literal, wrapped in single quotes.

Non-printable characters (see #printable?) are escaped.

'a'.inspect      # => "'a'"
'\t'.inspect     # => "'\\t'"
'あ'.inspect      # => "'あ'"
'\u0012'.inspect # => "'\\u0012'"
'😀'.inspect      # => "'\u{1F600}'"

See #unicode_escape for the format used to escape characters without a special escape sequence.

• #dump additionally escapes all non-ASCII characters.

Returns a representation of self as a Crystal char literal, wrapped in single quotes.

Non-printable characters (see #printable?) are escaped.

'a'.inspect      # => "'a'"
'\t'.inspect     # => "'\\t'"
'あ'.inspect      # => "'あ'"
'\u0012'.inspect # => "'\\u0012'"
'😀'.inspect      # => "'\u{1F600}'"

See #unicode_escape for the format used to escape characters without a special escape sequence.

• #dump additionally escapes all non-ASCII characters.

Returns true if this char is a letter.

All codepoints in the Unicode General Category L (Letter) are considered a letter.

'c'.letter? # => true
'á'.letter? # => true
'8'.letter? # => false

Returns true if this char is a lowercase letter.

'c'.lowercase? # => true
'ç'.lowercase? # => true
'G'.lowercase? # => false
'.'.lowercase? # => false

Returns true if this char is a mark character according to unicode.

Returns true if this char is a number according to unicode.

'1'.number? # => true
'a'.number? # => false

Returns the codepoint of this char.

The codepoint is the integer representation. The Universal Coded Character Set (UCS) standard, commonly known as Unicode, assigns names and meanings to numbers, these numbers are called codepoints.

For values below and including 127 this matches the ASCII codes and thus its byte representation.

'a'.ord      # => 97
'\0'.ord     # => 0
'\u007f'.ord # => 127
'☃'.ord      # => 9731

Returns the predecessor codepoint before this one.

This can be used for iterating a range of characters (see Range#each).

'b'.pred # => 'a'
'ぃ'.pred # => 'あ'

This does not always return codepoint - 1. There is a gap in the range of Unicode scalars: The surrogate codepoints U+D800 through U+DFFF.

'\uE000'.pred # => '\uD7FF'

Raises OverflowError for Char::ZERO.

• #succ returns the successor codepoint.

Returns true if this char is a printable character.

There is no universal definition of printable characters in Unicode. For the purpose of this method, all characters with a visible glyph and the ASCII whitespace () are considered printable.

This means characters which are #control? or #whitespace? (except for ) are non-printable.

Performs a #step in the direction of the limit. For instance:

'd'.step(to: 'a').to_a # => ['d', 'c', 'b', 'a']
'a'.step(to: 'd').to_a # => ['a', 'b', 'c', 'd']

Performs a #step in the direction of the limit. For instance:

'd'.step(to: 'a').to_a # => ['d', 'c', 'b', 'a']
'a'.step(to: 'd').to_a # => ['a', 'b', 'c', 'd']

Returns the successor codepoint after this one.

This can be used for iterating a range of characters (see Range#each).

'a'.succ # => 'b'
'あ'.succ # => 'ぃ'

This does not always return codepoint + 1. There is a gap in the range of Unicode scalars: The surrogate codepoints U+D800 through U+DFFF.

'\uD7FF'.succ # => '\uE000'

Raises OverflowError for Char::MAX.

• #pred returns the predecessor codepoint.

Returns the integer value of this char as a float if it's an ASCII char denoting a digit, raises otherwise.

'1'.to_f # => 1.0
'8'.to_f # => 8.0
'c'.to_f # raises ArgumentError

See also: #to_f.

See also: #to_f?.

Same as #to_f.

Same as #to_f?.

Returns the integer value of this char as a float if it's an ASCII char denoting a digit, nil otherwise.

'1'.to_f? # => 1.0
'8'.to_f? # => 8.0
'c'.to_f? # => nil

Returns the integer value of this char if it's an ASCII char denoting a digit in base, raises otherwise.

'1'.to_i     # => 1
'8'.to_i     # => 8
'c'.to_i     # raises ArgumentError
'1'.to_i(16) # => 1
'a'.to_i(16) # => 10
'f'.to_i(16) # => 15
'z'.to_i(16) # raises ArgumentError

See also: #to_i.

See also: #to_i?.

Same as #to_i.

Same as #to_i?.

See also: #to_i.

See also: #to_i?.

See also: #to_i.

See also: #to_i?.

Returns the integer value of this char if it's an ASCII char denoting a digit in base, nil otherwise.

'1'.to_i?     # => 1
'8'.to_i?     # => 8
'c'.to_i?     # => nil
'1'.to_i?(16) # => 1
'a'.to_i?(16) # => 10
'f'.to_i?(16) # => 15
'z'.to_i?(16) # => nil

Appends this char to the given IO.

This appends this char's bytes as encoded by UTF-8 to the given IO.

Returns this char as a string containing this char as a single character.

'a'.to_s # => "a"
'あ'.to_s # => "あ"

See also: #to_i.

See also: #to_i?.

See also: #to_i.

See also: #to_i?.

See also: #to_i.

See also: #to_i?.

See also: #to_i.

See also: #to_i?.

Returns the Unicode escape sequence representing this character.

The codepoints are expressed as hexadecimal digits with uppercase letters. Unicode escapes always use the four digit style for codepoints U+FFFF and lower, adding leading zeros when necessary. Higher codepoints have their digits wrapped in curly braces and no leading zeros.

'a'.unicode_escape      # => "\\u0061"
'\t'.unicode_escape     # => "\\u0009"
'あ'.unicode_escape      # => "\\u3042"
'\u0012'.unicode_escape # => "\\u0012"
'😀'.unicode_escape      # => "\\u{1F600}"

Returns the Unicode escape sequence representing this character.

The codepoints are expressed as hexadecimal digits with uppercase letters. Unicode escapes always use the four digit style for codepoints U+FFFF and lower, adding leading zeros when necessary. Higher codepoints have their digits wrapped in curly braces and no leading zeros.

'a'.unicode_escape      # => "\\u0061"
'\t'.unicode_escape     # => "\\u0009"
'あ'.unicode_escape      # => "\\u3042"
'\u0012'.unicode_escape # => "\\u0012"
'😀'.unicode_escape      # => "\\u{1F600}"

Returns the upcase equivalent of this char.

Note that this only works for characters whose upcase equivalent yields a single codepoint. There are a few characters, like 'ffl', than when upcased result in multiple characters (in this case: 'F', 'F', 'L').

For a more correct method see the method that receives a block.

'z'.upcase # => 'Z'
'X'.upcase # => 'X'
'.'.upcase # => '.'

Yields each char for the upcase equivalent of this char.

This method takes into account the possibility that an upcase version of a char might result in multiple chars, like for 'ffl', which results in 'F', 'F' and 'L'.

'z'.upcase { |v| puts v } # prints 'Z'
'ffl'.upcase { |v| puts v } # prints 'F', 'F', 'L'

Returns true if this char is an uppercase letter.

'H'.uppercase? # => true
'Á'.uppercase? # => true
'c'.uppercase? # => false
'.'.uppercase? # => false

Returns true if this char is a whitespace according to unicode.

' '.whitespace?  # => true
'\t'.whitespace? # => true
'b'.whitespace?  # => false