Comparing a rand to a range of numbers?

Question

Is there a function in Ruby that'll allow me to do what I'm attempting here?

rand1 = rand(10)

puts rand1
puts ""

if rand1 == (0..9)
  print "yes"
else
  print "no"
end

This prints out no, how could line 6 be altered so that this will print out yes?

Possible duplicate of [Determining if a variable is within range?](https://stackoverflow.com/questions/870507/determining-if-a-variable-is-within-range) — Viktor, Oct 27 '19 at 09:57
It would be helpful if you could explain what, *exactly* is unclear to you about the documentation of `Range`. That way, the Ruby developers can improve the documentation so that future developers don't stumble across the same problems you did. Help make the world a better place! — Jörg W Mittag, Oct 27 '19 at 10:32
@seasonalz : You are testing whether an object of class `Integer` is **equal** to an object of class `Range`.Of course you get false. An apple is not a pear. What do you want to achieve here? — user1934428, Oct 28 '19 at 10:31

Stefan · Answer 1 · 2019-10-27T10:05:06.070

case rand
when 0..9
  print 'yes'
else 
  print 'no'
end

It also allows you to provide multiple ranges or numbers to compare against. Here's a contrived example:

case rand
when 0..2, 3, 4..9
  print 'yes'
else 
  print 'no'
end

Under the hood, case uses === to compare the given objects, i.e. the above is (almost) equivalent to:

if 0..2 === rand || 3 === rand || 4..9 === rand
  print 'yes'
else
  print 'no'
end

(note that the when objects become the receiver and rand becomes the argument)

score 3 · Answer 2 · answered Oct 27 '19 at 09:52

3

You can use Range#cover? which works like === in this case.

irb(main):001:0> (0..9).cover?(0.1)
=> true

answered Oct 27 '19 at 09:52

max

score 1 · Answer 3 · answered Oct 27 '19 at 09:15

It's simple, use ===

rand1 = rand(10)

puts rand1
puts ""

if (0..9) === rand1
  print "yes"
else
  print "no"
end

Note: rand1===(0..9) won't work

And also you can use member?

rand1 = rand(10)

puts rand1
puts ""

if (0..9).member?(rand1)
  print "yes"
else
  print "no"
end

score 0 · Answer 4 · answered Oct 27 '19 at 11:33

0

Not the best option but yet an option (not covered here: Determining if a variable is within range?)

rand1 >= (0..9).begin && rand1 <= (0..9).end

answered Oct 27 '19 at 11:33

iGian

4 Answers4