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

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?

Answers


(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

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

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

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

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: 1, message: 'must be between 0 & 100'

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


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.


Need Your Help

What is so evil about a Flash based website?

html flash silverlight

I have the feeling that Flash-based ( or Silverlight-based) websites are generally frowned upon, except when you are creating games or multimedia-content rich applications. Why this is so?

Why would code actively try to prevent tail-call optimization?

c++ c optimization compiler-optimization tail-call-optimization

The title of the question might be a bit strange, but the thing is that, as far as I know, there is nothing that speaks against tail call optimization at all. However, while browsing open source pr...