Returns the OLE variable name and the value with class name.
Return the contents of this hash as a string.
h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300 } h.to_s #=> "{\"c\"=>300, \"a\"=>100, \"d\"=>400}"
Associates the value given by value with the key given by key.
h = { "a" => 100, "b" => 200 } h["a"] = 9 h["c"] = 4 h #=> {"a"=>9, "b"=>200, "c"=>4} h.store("d", 42) #=> 42 h #=> {"a"=>9, "b"=>200, "c"=>4, "d"=>42}
key should not have its value changed while it is in use as a key (an unfrozen String passed as a key will be duplicated and frozen).
a = "a" b = "b".freeze h = { a => 100, b => 200 } h.key(100).equal? a #=> false h.key(200).equal? b #=> true
Returns the number of key-value pairs in the hash.
h = { "d" => 100, "a" => 200, "v" => 300, "e" => 400 } h.size #=> 4 h.delete("a") #=> 200 h.size #=> 3 h.length #=> 3
Hash#length is an alias for Hash#size.
Returns a new hash created by using hsh’s values as keys, and the keys as values. If a key with the same value already exists in the hsh, then the last one defined will be used, the earlier value(s) will be discarded.
h = { "n" => 100, "m" => 100, "y" => 300, "d" => 200, "a" => 0 } h.invert #=> {0=>"a", 100=>"m", 200=>"d", 300=>"y"}
If there is no key with the same value, Hash#invert is involutive.
h = { a: 1, b: 3, c: 4 } h.invert.invert == h #=> true
The condition, no key with the same value, can be tested by comparing the size of inverted hash.
# no key with the same value h = { a: 1, b: 3, c: 4 } h.size == h.invert.size #=> true # two (or more) keys has the same value h = { a: 1, b: 3, c: 1 } h.size == h.invert.size #=> false
Returns true if the given key is present in hsh.
h = { "a" => 100, "b" => 200 } h.has_key?("a") #=> true h.has_key?("z") #=> false
Note that include? and member? do not test member equality using == as do other Enumerables.
See also Enumerable#include?
ENV.store is an alias for ENV.[]=.
Creates, updates, or deletes the named environment variable, returning the value. Both name and value may be instances of String. See Valid Names and Values.
If the named environment variable does not exist:
If value is nil, does nothing.
ENV.clear ENV['foo'] = nil # => nil ENV.include?('foo') # => false ENV.store('bar', nil) # => nil ENV.include?('bar') # => false
If value is not nil, creates the environment variable with name and value:
# Create 'foo' using ENV.[]=. ENV['foo'] = '0' # => '0' ENV['foo'] # => '0' # Create 'bar' using ENV.store. ENV.store('bar', '1') # => '1' ENV['bar'] # => '1'
If the named environment variable exists:
If value is not nil, updates the environment variable with value value:
# Update 'foo' using ENV.[]=. ENV['foo'] = '2' # => '2' ENV['foo'] # => '2' # Update 'bar' using ENV.store. ENV.store('bar', '3') # => '3' ENV['bar'] # => '3'
If value is nil, deletes the environment variable:
# Delete 'foo' using ENV.[]=. ENV['foo'] = nil # => nil ENV.include?('foo') # => false # Delete 'bar' using ENV.store. ENV.store('bar', nil) # => nil ENV.include?('bar') # => false
Raises an exception if name or value is invalid. See Invalid Names and Values.
Returns a new hash created by using environment variable names as values and values as names.
Returns the contents of the environment as a String.
Deprecated method that is equivalent to ENV.key
Returns the number of environment variables.
ENV.has_key?, ENV.member?, and ENV.key? are aliases for ENV.include?.
Returns true if there is an environment variable with the given name:
ENV.replace('foo' => '0', 'bar' => '1') ENV.include?('foo') # => true
Returns false if name is a valid String and there is no such environment variable:
ENV.include?('baz') # => false
Returns false if name is the empty String or is a String containing character '=':
ENV.include?('') # => false ENV.include?('=') # => false
Raises an exception if name is a String containing the NUL character "\0":
ENV.include?("\0") # Raises ArgumentError (bad environment variable name: contains null byte)
Raises an exception if name has an encoding that is not ASCII-compatible:
ENV.include?("\xa1\xa1".force_encoding(Encoding::UTF_16LE)) # Raises ArgumentError (bad environment variable name: ASCII incompatible encoding: UTF-16LE)
Raises an exception if name is not a String:
ENV.include?(Object.new) # TypeError (no implicit conversion of Object into String)
This is a deprecated alias for each_line.
This is a deprecated alias for each_codepoint.
Reads ARGF‘s current file in its entirety, returning an Array of its lines, one line per element. Lines are assumed to be separated by sep.
lines = ARGF.readlines lines[0] #=> "This is line one\n"
Returns the next line from the current file in ARGF.
By default lines are assumed to be separated by $/; to use a different character as a separator, supply it as a String for the sep argument.
The optional limit argument specifies how many characters of each line to return. By default all characters are returned.
An EOFError is raised at the end of the file.
Positions the current file to the beginning of input, resetting ARGF.lineno to zero.
ARGF.readline #=> "This is line one\n" ARGF.rewind #=> 0 ARGF.lineno #=> 0 ARGF.readline #=> "This is line one\n"
Puts ARGF into binary mode. Once a stream is in binary mode, it cannot be reset to non-binary mode. This option has the following effects:
Newline conversion is disabled.
Encoding conversion is disabled.
Content is treated as ASCII-8BIT.
Returns true if ARGF is being read in binary mode; false otherwise. To enable binary mode use ARGF.binmode.
For example:
ARGF.binmode? #=> false ARGF.binmode ARGF.binmode? #=> true
Writes string if inplace mode.
Returns the current line number of ARGF as a whole. This value can be set manually with ARGF.lineno=.
For example:
ARGF.lineno #=> 0 ARGF.readline #=> "This is line 1\n" ARGF.lineno #=> 1
Sets the line number of ARGF as a whole to the given Integer.
ARGF sets the line number automatically as you read data, so normally you will not need to set it explicitly. To access the current line number use ARGF.lineno.
For example:
ARGF.lineno #=> 0 ARGF.readline #=> "This is line 1\n" ARGF.lineno #=> 1 ARGF.lineno = 0 #=> 0 ARGF.lineno #=> 0
Returns “ARGF”.
Synonym for $stdout.
Alias for CSV::read().