如何找到一个更大的版本号?

When compare two version strings, to_f does not work well:

当比较两个版本字符串时，to_f不能很好地工作:

 > "1.5.8".to_f > "1.5.7".to_f
  => false

string comparison is better, but not always correct:

字符串比较更好，但并不总是正确的:

 > "1.5.8" > "1.5.7"
  => true 

 > "1.5.8" > "1.5.9"
  => false 

 > "1.5.8" > "1.5.10" # oops!
  => true

How to compare version strings properly?

如何正确地比较版本字符串?

3 个解决方案

#1

An idea: create a Object#compare_by method that behaves like compare (aka the spaceship operator Object#<=>) but takes a custom block:

一个想法:创建一个对象#compare_by方法，它的行为类似于compare(也就是太空船操作员对象#<=>)，但它采用了一个自定义块:

class Object
  def compare_by(other)
    yield(self) <=> yield(other)
  end
end

>> "1.5.2".compare_by("1.5.7") { |s| s.split(".").map(&:to_i) }
#=> -1

You can also take a more specific approach still based on the compare method:

您还可以基于比较方法采取更具体的方法:

class String
  def compare_by_fields(other, fieldsep = ".")
    cmp = proc { |s| s.split(fieldsep).map(&:to_i) }
    cmp.call(self) <=> cmp.call(other)
  end
end

>> "1.5.8".compare_by_fields("1.5.8")
#=> 0

#2

Personally I'd probably just use the Versionomy gem, no need to reinvent this specific wheel IMHO.

就我个人而言，我可能只是使用了Versionomy gem，没有必要重新发明这个特定的*IMHO。

Example:

例子:

require 'versionomy'
v1 = Versionomy.parse("1.5.8")
v2 = Versionomy.parse("1.5.10")
v2 > v1
#=> true

#3

First start off by splitting the different parts of the versions:

首先，将版本的不同部分分开:

v1 = "1.5.8"
v2 = "1.5.7"
v1_arr = v1.split(".")
=> ["1", "5", "8"]
v2_arr = v2.split(".")
=> ["1", "5", "7"]
v1_arr.size.times do |index|
   if v1_arr[index] != v2_arr[index]
     # compare the values at the given index. Don't forget to use to_i!
     break
   end
end

#1