Ruby-on-rails 如何检查一个数字是否包含在一个范围内（在一个语句中）？
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How to check if a number is included in a range (in one statement)?
提问by Backo
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 = 5I would like to check 1 <= number <= 10and retrieve a boolean value if the numbervalue is included in that range.
我正在使用 Ruby on Rails 3.0.9，我想检查一个数字是否包含在一个范围内。也就是说，如果我有一个变量，如果该值包含在该范围内，number = 5我想检查1 <= number <= 10并检索一个布尔值number。
I can do that like this:
我可以这样做：
number >= 1 && number <= 10
but I would like to do that in one statement. How can I do that?
但我想在一份声明中做到这一点。我怎样才能做到这一点？
回答by Mario Uher
(1..10).include?(number)is the trick.
(1..10).include?(number)是诀窍。
Btw: If you want to validate a number using ActiveModel::Validations, you can even do:
顺便说一句：如果你想使用 验证一个数字ActiveModel::Validations，你甚至可以这样做：
validates_inclusion_of :number, :in => 1..10
read hereabout validates_inclusion_of
在此处阅读有关 validates_inclusion_of 的信息
or the Rails 3+ way:
或 Rails 3+ 方式：
validates :number, :inclusion => 1..10
回答by tybro0103
(1..10).include? n
(1..10).cover? n
n.between? 1, 10
validates :n, numericality: {only_integer: true, greater_than_or_equal_to: 1, less_than_or_equal_to: 10}
validates :n, inclusion: 1..10
回答by Holin
If it's not part of a validation process you can use #between?:
如果它不是验证过程的一部分，您可以使用#between?：
2.between?(1, 4)
=> true
回答by Jon
For accurate error messages on a form submit , try these
要在表单提交上获得准确的错误消息，请尝试这些
validates_numericality_of :tax_rate, greater_than_or_equal_to: 0, less_than_or_equal_to: 1, message: 'must be between 0 & 100'
回答by Sudhir Vishwakarma
Rails 4
导轨 4
if you want it through ActiveModel::Validations you can use
如果你想通过 ActiveModel::Validations 你可以使用
validates_inclusion_of :number, :in => start_number..end_number
or the Rails 3 syntax
或 Rails 3 语法
validates :number, :inclusion => start_number..end_number
But The simplest way i find is
但我发现的最简单的方法是
number.between? start_number, end_number
number.between? start_number, end_number
回答by Michael Kohl
In Ruby 1.9 the most direct translation seems to be Range#cover?:
在 Ruby 1.9 中，最直接的翻译似乎是Range#cover？：
Returns true if obj is between beg and end, i.e beg <= obj <= end (or end exclusive when exclude_end? is true).
如果 obj 介于 beg 和 end 之间，即 beg <= obj <= end（或当 exclude_end? 为真时为 end exclusive），则返回 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 postfor a more detailed explanation.
如果您想知道这与 有Range#include?什么不同，如果它是非数字范围，后者将迭代范围的所有元素。有关更详细的解释，请参阅此博客文章。
回答by Lakhani Aliraza
If you want to check particular number exists in custom array,
如果要检查自定义数组中是否存在特定数字，
As for example I want to know whether 5 is included in list=[1,4,6,10] or not
例如，我想知道 list=[1,4,6,10] 中是否包含 5
list.include? 5 => false
list.include? 6 => true
