Ref. WGR Chapter 9, Collection and container objects, Section 9.4, Ranges
Two dots: inclusive
up_to_100 = 1..100
Three dots: exclusive
up_to_99 = 1...100
>> (1..10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>> (1..10).map{|x| x*2}
=> [2, 4, 6, 8, 10, 12, 14, 16, 18, 20]
>> alphabet = "a".."z"
=> "a".."z"
>> alphabet.to_a
=> ["a", "b", "c", "d", "e", "f",
"g", "h", "i", "j", "k", "l",
"m", "n", "o", "p", "q", "r",
"s", "t", "u", "v", "w", "x",
"y", "z"]
Ranges are primarily used for
looping
(1..10).each do |i|
puts "#{i} mississippi"
end
string or array indexing
>> "my bologna has a first name"[3..10]
=> "bologna "
```ruby
>> up_to_10 = 1..10
=> 1..10
>> up_to_10.begin
=> 1
>> up_to_10.end
=> 10
>> up_to_10.exclude_end?
=> false
>> up_to_10.include? 5
=> true
>> up_to_10.include? 15
=> false
>> alphabet.include? "c"
=> true
>> alphabet.include? "abc"
=> false
>> alphabet.cover? "abc"
=> true
cover? just checks whether the parameter falls between the endpoints, not whether it is inside the virtual array
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