Calls the block with each repeated combination of length n
of the elements of self
; each combination is an Array; returns self
. The order of the combinations is indeterminate.
When a block and a positive Integer argument n
are given, calls the block with each n
-tuple repeated combination of the elements of self
. The number of combinations is (n+1)(n+2)/2
.
n
= 1:
a = [0, 1, 2] a.repeated_combination(1) {|combination| p combination }
Output:
[0] [1] [2]
n
= 2:
a.repeated_combination(2) {|combination| p combination }
Output:
[0, 0] [0, 1] [0, 2] [1, 1] [1, 2] [2, 2]
If n
is zero, calls the block once with an empty Array.
If n
is negative, does not call the block:
a.repeated_combination(-1) {|combination| fail 'Cannot happen' }
Returns a new Enumerator if no block given:
a = [0, 1, 2] a.repeated_combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
Using Enumerators, it’s convenient to show the combinations and counts for some values of n
:
e = a.repeated_combination(0) e.size # => 1 e.to_a # => [[]] e = a.repeated_combination(1) e.size # => 3 e.to_a # => [[0], [1], [2]] e = a.repeated_combination(2) e.size # => 6 e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 1], [1, 2], [2, 2]]
Searches self
as described at method bsearch
, but returns the index of the found element instead of the element itself.
Returns the singleton class of obj. This method creates a new singleton class if obj does not have one.
If obj is nil
, true
, or false
, it returns NilClass
, TrueClass
, or FalseClass
, respectively. If obj is an Integer
, a Float
or a Symbol
, it raises a TypeError
.
Object.new.singleton_class #=> #<Class:#<Object:0xb7ce1e24>> String.singleton_class #=> #<Class:String> nil.singleton_class #=> NilClass
Returns an array of the names of singleton methods for obj. If the optional all parameter is true, the list will include methods in modules included in obj. Only public and protected singleton methods are returned.
module Other def three() end end class Single def Single.four() end end a = Single.new def a.one() end class << a include Other def two() end end Single.singleton_methods #=> [:four] a.singleton_methods(false) #=> [:two, :one] a.singleton_methods #=> [:two, :one, :three]
Returns an array of instance variable names for the receiver. Note that simply defining an accessor does not create the corresponding instance variable.
class Fred attr_accessor :a1 def initialize @iv = 3 end end Fred.new.instance_variables #=> [:@iv]
Returns true
if obj is an instance of the given class. See also Object#kind_of?
.
class A; end class B < A; end class C < B; end b = B.new b.instance_of? A #=> false b.instance_of? B #=> true b.instance_of? C #=> false
Returns true
if class is the class of obj, or if class is one of the superclasses of obj or modules included in obj.
module M; end class A include M end class B < A; end class C < B; end b = B.new b.is_a? A #=> true b.is_a? B #=> true b.is_a? C #=> false b.is_a? M #=> true b.kind_of? A #=> true b.kind_of? B #=> true b.kind_of? C #=> false b.kind_of? M #=> true
Similar to method, searches singleton method only.
class Demo def initialize(n) @iv = n end def hello() "Hello, @iv = #{@iv}" end end k = Demo.new(99) def k.hi "Hi, @iv = #{@iv}" end m = k.singleton_method(:hi) m.call #=> "Hi, @iv = 99" m = k.singleton_method(:hello) #=> NameError
Since int
is already an Integer
, returns self
.
Returns self
as an integer; converts using method to_i
in the derived class.
Of the Core and Standard Library classes, only Rational
and Complex
use this implementation.
Examples:
Rational(1, 2).to_int # => 0 Rational(2, 1).to_int # => 2 Complex(2, 0).to_int # => 2 Complex(2, 1) # Raises RangeError (non-zero imaginary part)
Replaces the contents of self
with the contents of other_string
:
s = 'foo' # => "foo" s.replace('bar') # => "bar"
Splits str using the supplied parameter as the record separator ($/
by default), passing each substring in turn to the supplied block. If a zero-length record separator is supplied, the string is split into paragraphs delimited by multiple successive newlines.
If chomp
is true
, separator
will be removed from the end of each line.
If no block is given, an enumerator is returned instead.
"hello\nworld".each_line {|s| p s} # prints: # "hello\n" # "world" "hello\nworld".each_line('l') {|s| p s} # prints: # "hel" # "l" # "o\nworl" # "d" "hello\n\n\nworld".each_line('') {|s| p s} # prints # "hello\n\n" # "world" "hello\nworld".each_line(chomp: true) {|s| p s} # prints: # "hello" # "world" "hello\nworld".each_line('l', chomp: true) {|s| p s} # prints: # "he" # "" # "o\nwor" # "d"
Passes the Integer
ordinal of each character in str, also known as a codepoint when applied to Unicode strings to the given block. For encodings other than UTF-8/UTF-16(BE|LE)/UTF-32(BE|LE), values are directly derived from the binary representation of each character.
If no block is given, an enumerator is returned instead.
"hello\u0639".each_codepoint {|c| print c, ' ' }
produces:
104 101 108 108 111 1593
Changes the encoding to encoding
and returns self.
Returns true for a string which is encoded correctly.
"\xc2\xa1".force_encoding("UTF-8").valid_encoding? #=> true "\xc2".force_encoding("UTF-8").valid_encoding? #=> false "\x80".force_encoding("UTF-8").valid_encoding? #=> false
Unicode Normalization—Returns a normalized form of str
, using Unicode normalizations NFC, NFD, NFKC, or NFKD. The normalization form used is determined by form
, which can be any of the four values :nfc
, :nfd
, :nfkc
, or :nfkd
. The default is :nfc
.
If the string is not in a Unicode Encoding
, then an Exception
is raised. In this context, ‘Unicode Encoding’ means any of UTF-8, UTF-16BE/LE, and UTF-32BE/LE, as well as GB18030, UCS_2BE, and UCS_4BE. Anything other than UTF-8 is implemented by converting to UTF-8, which makes it slower than UTF-8.
"a\u0300".unicode_normalize #=> "\u00E0" "a\u0300".unicode_normalize(:nfc) #=> "\u00E0" "\u00E0".unicode_normalize(:nfd) #=> "a\u0300" "\xE0".force_encoding('ISO-8859-1').unicode_normalize(:nfd) #=> Encoding::CompatibilityError raised
Destructive version of String#unicode_normalize
, doing Unicode normalization in place.
Checks whether str
is in Unicode normalization form form
, which can be any of the four values :nfc
, :nfd
, :nfkc
, or :nfkd
. The default is :nfc
.
If the string is not in a Unicode Encoding
, then an Exception
is raised. For details, see String#unicode_normalize
.
"a\u0300".unicode_normalized? #=> false "a\u0300".unicode_normalized?(:nfd) #=> true "\u00E0".unicode_normalized? #=> true "\u00E0".unicode_normalized?(:nfd) #=> false "\xE0".force_encoding('ISO-8859-1').unicode_normalized? #=> Encoding::CompatibilityError raised
Returns self
truncated to an Integer
.
1.2.to_i # => 1 (-1.2).to_i # => -1
Note that the limited precision of floating-point arithmetic may lead to surprising results:
(0.3 / 0.1).to_i # => 2 (!)
Float#to_int
is an alias for Float#to_i
.
Returns default internal encoding. Strings will be transcoded to the default internal encoding in the following places if the default internal encoding is not nil:
File
data read from disk
Strings returned from Readline
Strings returned from SDBM
Values from ENV
Values in ARGV including $PROGRAM_NAME
Additionally String#encode
and String#encode!
use the default internal encoding if no encoding is given.
The script encoding (__ENCODING__), not default_internal
, is used as the encoding of created strings.
Encoding::default_internal
is initialized with -E option or nil otherwise.
Sets default internal encoding or removes default internal encoding when passed nil. You should not set Encoding::default_internal
in ruby code as strings created before changing the value may have a different encoding from strings created after the change. Instead you should use ruby -E
to invoke ruby with the correct default_internal.
See Encoding::default_internal
for information on how the default internal encoding is used.
Returns the locale charmap name. It returns nil if no appropriate information.
Debian GNU/Linux LANG=C Encoding.locale_charmap #=> "ANSI_X3.4-1968" LANG=ja_JP.EUC-JP Encoding.locale_charmap #=> "EUC-JP" SunOS 5 LANG=C Encoding.locale_charmap #=> "646" LANG=ja Encoding.locale_charmap #=> "eucJP"
The result is highly platform dependent. So Encoding.find(Encoding.locale_charmap)
may cause an error. If you need some encoding object even for unknown locale, Encoding.find
(“locale”) can be used.
Iterates the given block for each element with an index, which starts from offset
. If no block is given, returns a new Enumerator
that includes the index, starting from offset
offset
the starting index to use
Invoked as a callback whenever an instance method is undefined from the receiver.
module Chatty def self.method_undefined(method_name) puts "Undefining #{method_name.inspect}" end def self.some_class_method() end def some_instance_method() end class << self undef_method :some_class_method end undef_method :some_instance_method end
produces:
Undefining :some_instance_method