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In irb
[[]] | [3]
produces
[[], 3]
I am having some difficulty understanding it. How is the OR operator working here ?
According to the documentation,
Set Union — Returns a new array by joining ary with other_ary,
excluding any duplicates and preserving the order from the original
array.
[1,2,3] | [4,5,6] # => [1, 2, 3, 4, 5, 6]
[1,2,3] | [4,1,2] # => [1, 2, 3, 4]
|| is the logical OR operator you might be thinking of.
| with arrays performs a set union operation on the arrays and gives you an array that has all the unique elements of both arrays. More details at ruby-doc
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I have:
str = "something"
str[0, 1] #=> "s"
str[0, 2] #=> "so"
str[3, 4] #=> "ethi"
str[2, 3] #=> "meth"
I can't see logic in this. What is returned by this double indexes?
str[2,3] is "met". In this form it is str[zero_based_start_position, number_of_characters]
See ruby documentation on String class
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Closed 7 years ago.
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myhash = {answer: "yes", something: hello, another: "yes"}
myhash.delete[another]
I want to delete the another key-value pair. But, ruby gives me an error saying wrong number of arguments (0 for 1). What's going on?
the method delete is a method, not an element on the hash , and another key is a symbol, so you should call on this form
myhash.delete(:another)
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If I have a hash
{"one"=>1, "two"=>2, "three"=>3}
What is the best way to map the keys to get the array:
["one", "two", "three"]
{"one"=>1, "two"=>2, "three"=>3}.keys #=> ["one", "two", "three"]
The documentation is awesome for discovering answers to questions like these.
If the question is "how do I get X data from object of type Y?", reading through the docs for object type Y should be the first place you go.
{"one"=>1, "two"=>2, "three"=>3}.keys
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tickets = Array.new(5) {rand(10)+1}
How can I make a ruby code, that checks if any tickets equals, for example 5. I want output something like
=> "Ticket #5 wins!"
So - if tickets generate 1, 5, 4, 2, 3 and my rule is it to equal 5, it outputs
=> "Ticket #5 wins!"
To check if an array includes an element and print the result.
winner = 5
puts "Ticket ##{winner} wins!" if tickets.include? winner
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If i use Prime class like this:
Prime.new
I'll get next message:
Prime::new is obsolete. use Prime::instance or class methods of Prime.
I tryied finding this class documentation, but couldn't.
Unfortunately it seems not to be published yet at ruby-doc.org. But you could have a look at the commented source code for now; it includes usage examples.
You should have it locally through ri:
$ ri Prime
= Prime < Object
------------------------------------------------------------------------------
= Includes:
Enumerable (from ruby core)
(from ruby core)
------------------------------------------------------------------------------
The set of all prime numbers.
== Example
Prime.each(100) do |prime|
p prime #=> 2, 3, 5, 7, 11, ...., 97
end
== Retrieving the instance
Prime.new is obsolete. Now Prime has the default instance and you can access
it as Prime.instance.
...
There's also RubyDoc.info which has a better index:
http://rubydoc.info/stdlib/prime/1.9.2/frames