How to check if a number is included in a range (in one statement)?

Question

I am using Ruby on Rails 3.0.9 and I would like to check if a number is included in a range. That is, if I have a variable number = 5 I would like to check 1 <= number <= 10 and retrieve a boolean value if the number value is included in that range.

I can do that like this:

number >= 1 && number <= 10

but I would like to do that in one statement. How can I do that?

Since there's nothing wrong with your cited statement it begs the question: why do want/need to further "shorten" it ? — DarkDust, Jul 30 '11 at 08:07

score 179 · Accepted Answer · edited Apr 25 '20 at 06:07

179

(1..10).include?(number) is the trick.

Btw: If you want to validate a number using ActiveModel::Validations, you can even do:

validates_inclusion_of :number, :in => 1..10

read here about validates_inclusion_of

or the Rails 3+ way:

validates :number, :inclusion => 1..10

edited Apr 25 '20 at 06:07

BananaNeil

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answered Jul 30 '11 at 07:59

Mario Uher

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What if I want also to allow nil? I'm getting an error when it's nil. – user2503775 Jan 07 '14 at 14:45
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Rails has a option `allow_nil`. Just add it like so: `, allow_nil: true` – Mario Uher Jan 07 '14 at 14:48

tybro0103 · Answer 2 · 2014-01-03T18:11:41.323

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Enumerable#include?:

(1..10).include? n

Range#cover?:

(1..10).cover? n

Comparable#between?:

n.between? 1, 10

Numericality Validator:

validates :n, numericality: {only_integer: true, greater_than_or_equal_to: 1, less_than_or_equal_to: 10}

Inclusion Validator:

validates :n, inclusion: 1..10

edited Jan 03 '14 at 18:11

answered Jul 02 '12 at 20:08

tybro0103

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I like this method better, because the validation text makes more sense. – Dan Jun 18 '13 at 15:19
I like it better because I was already validation numericality. Makes it a one-line :) – BradGreens Sep 12 '13 at 01:13
@BradGreens that's one long line. – wchargin Dec 27 '13 at 06:06
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I want to note that u can use proc if u need some specific logic or access to associations. For example `validates :amount, numericality: { less_than_or_equal_to: ->(m) { m.user.balance }, greater_than_or_equal_to: 0 }` – Евгений Масленков Mar 22 '16 at 12:02

score 16 · Answer 3 · answered Jul 30 '11 at 15:52

16

If it's not part of a validation process you can use #between? :

2.between?(1, 4)
=> true

answered Jul 30 '11 at 15:52

Holin

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score 9 · Answer 4 · edited Oct 16 '20 at 19:28

9

For accurate error messages on a form submit , try these

validates_numericality_of :tax_rate, greater_than_or_equal_to: 0, less_than_or_equal_to: 100, message: 'must be between 0 & 100'

edited Oct 16 '20 at 19:28

jeffdill2

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answered Jul 28 '17 at 02:08

Jon

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Sudhir Vishwakarma · Answer 5 · 2016-05-28T04:16:31.250

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Rails 4

if you want it through ActiveModel::Validations you can use

validates_inclusion_of :number, :in => start_number..end_number

or the Rails 3 syntax

validates :number, :inclusion => start_number..end_number

But The simplest way i find is

number.between? start_number, end_number

edited May 28 '16 at 04:16

answered May 26 '16 at 07:38

Sudhir Vishwakarma

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Perhaps include some explanation. – GMchris May 26 '16 at 11:33

score 2 · Answer 6 · answered Jul 02 '12 at 21:03

In Ruby 1.9 the most direct translation seems to be Range#cover?:

Returns true if obj is between beg and end, i.e beg <= obj <= end (or end exclusive when exclude_end? is true).

In case you wonder how that's different from Range#include?, it's that the latter iterates over all elements of the range if it's a non-numeric range. See this blog post for a more detailed explanation.

score 1 · Answer 7 · answered Aug 08 '19 at 18:15

1

If you want to check particular number exists in custom array,

As for example I want to know whether 5 is included in list=[1,4,6,10] or not

list.include? 5 => false
list.include? 6 => true

answered Aug 08 '19 at 18:15

Lakhani Aliraza

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How to check if a number is included in a range (in one statement)?

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