Returns the first element or elements.
With no argument, returns the first element, or nil if there is none:
(1..4).first # => 1 %w[a b c].first # => "a" {foo: 1, bar: 1, baz: 2}.first # => [:foo, 1] [].first # => nil
With integer argument n, returns an array containing the first n elements that exist:
(1..4).first(2) # => [1, 2] %w[a b c d].first(3) # => ["a", "b", "c"] %w[a b c d].first(50) # => ["a", "b", "c", "d"] {foo: 1, bar: 1, baz: 2}.first(2) # => [[:foo, 1], [:bar, 1]] [].first(2) # => []
Returns a Digest subclass by name
require 'openssl' OpenSSL::Digest("MD5") # => OpenSSL::Digest::MD5 Digest("Foo") # => NameError: wrong constant name Foo
Returns a Digest subclass by name
require 'openssl' OpenSSL::Digest("MD5") # => OpenSSL::Digest::MD5 Digest("Foo") # => NameError: wrong constant name Foo
Disables garbage collection, returning true if garbage collection was already disabled.
GC.disable #=> false GC.disable #=> true
Returns a string usable in Dir.glob to match all requirable paths for this spec.
Creates a new directory in the tar file name with mode
Dispatches a single event for ‘node` to all registered listeners.
def dispatch_once: (Node) -> void
Calls the given block once for each key, value pair in the database.
Returns self.
Iterates over keys and values. Note that unlike other collections, each without block isn’t supported.
@api private
Calls the given block with each successive character from self; returns self:
'hello'.each_char {|char| print char, ' ' } print "\n" 'тест'.each_char {|char| print char, ' ' } print "\n" 'こんにちは'.each_char {|char| print char, ' ' } print "\n"
Output:
h e l l o т е с т こ ん に ち は
Returns an enumerator if no block is given.
Changes the encoding of self to encoding, which may be a string encoding name or an Encoding object; returns self:
s = 'łał' s.bytes # => [197, 130, 97, 197, 130] s.encoding # => #<Encoding:UTF-8> s.force_encoding('ascii') # => "\xC5\x82a\xC5\x82" s.encoding # => #<Encoding:US-ASCII>
Does not change the underlying bytes:
s.bytes # => [197, 130, 97, 197, 130]
Makes the change even if the given encoding is invalid for self (as is the change above):
s.valid_encoding? # => false s.force_encoding(Encoding::UTF_8) # => "łał" s.valid_encoding? # => true
Returns true if self is encoded correctly, false otherwise:
"\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
Returns the number of decimal significant digits in self.
BigDecimal("0").n_significant_digits # => 0 BigDecimal("1").n_significant_digits # => 1 BigDecimal("1.1").n_significant_digits # => 2 BigDecimal("3.1415").n_significant_digits # => 5 BigDecimal("-1e20").n_significant_digits # => 1 BigDecimal("1e-20").n_significant_digits # => 1 BigDecimal("Infinity").n_significant_digits # => 0 BigDecimal("-Infinity").n_significant_digits # => 0 BigDecimal("NaN").n_significant_digits # => 0
Converts a BigDecimal to a String of the form “nnnnnn.mmm”. This method is deprecated; use BigDecimal#to_s(“F”) instead.
require 'bigdecimal/util' d = BigDecimal("3.14") d.to_digits # => "3.14"
Returns true if the arguments define a valid ordinal date, false otherwise:
Date.valid_ordinal?(2001, 34) # => true Date.valid_ordinal?(2001, 366) # => false
See argument start.
Related: Date.jd, Date.ordinal.
Calls the given block with each character in the stream; returns self. See Character IO.
f = File.new('t.rus') a = [] f.each_char {|c| a << c.ord } a # => [1090, 1077, 1089, 1090] f.close
Returns an Enumerator if no block is given.
Related: IO#each_byte, IO#each_codepoint.
Returns the Encoding object that represents the encoding of the stream, or nil if the stream is in write mode and no encoding is specified.
See Encodings.
Returns the Encoding object that represents the encoding of the internal string, if conversion is specified, or nil otherwise.
See Encodings.
See Encodings.
Argument ext_enc, if given, must be an Encoding object or a String with the encoding name; it is assigned as the encoding for the stream.
Argument int_enc, if given, must be an Encoding object or a String with the encoding name; it is assigned as the encoding for the internal string.
Argument 'ext_enc:int_enc', if given, is a string containing two colon-separated encoding names; corresponding Encoding objects are assigned as the external and internal encodings for the stream.
If the external encoding of a string is binary/ASCII-8BIT, the internal encoding of the string is set to nil, since no transcoding is needed.
Optional keyword arguments enc_opts specify Encoding options.
Returns false if self is applicable to a string with any ASCII-compatible encoding; otherwise returns true:
r = /a/ # => /a/ r.fixed_encoding? # => false r.match?("\u{6666} a") # => true r.match?("\xa1\xa2 a".force_encoding("euc-jp")) # => true r.match?("abc".force_encoding("euc-jp")) # => true r = /a/u # => /a/ r.fixed_encoding? # => true r.match?("\u{6666} a") # => true r.match?("\xa1\xa2".force_encoding("euc-jp")) # Raises exception. r.match?("abc".force_encoding("euc-jp")) # => true r = /\u{6666}/ # => /\u{6666}/ r.fixed_encoding? # => true r.encoding # => #<Encoding:UTF-8> r.match?("\u{6666} a") # => true r.match?("\xa1\xa2".force_encoding("euc-jp")) # Raises exception. r.match?("abc".force_encoding("euc-jp")) # => false
Iterates over the children of the directory (files and subdirectories, not recursive).
It yields Pathname object for each child.
By default, the yielded pathnames will have enough information to access the files.
If you set with_directory to false, then the returned pathnames will contain the filename only.
Pathname("/usr/local").each_child {|f| p f } #=> #<Pathname:/usr/local/share> # #<Pathname:/usr/local/bin> # #<Pathname:/usr/local/games> # #<Pathname:/usr/local/lib> # #<Pathname:/usr/local/include> # #<Pathname:/usr/local/sbin> # #<Pathname:/usr/local/src> # #<Pathname:/usr/local/man> Pathname("/usr/local").each_child(false) {|f| p f } #=> #<Pathname:share> # #<Pathname:bin> # #<Pathname:games> # #<Pathname:lib> # #<Pathname:include> # #<Pathname:sbin> # #<Pathname:src> # #<Pathname:man>
Note that the results never contain the entries . and .. in the directory because they are not children.