如何在Ruby中重写这个JavaScript循环？

Question

Code:

var some_var = [/*.......*/];
var compare_var;
for (var i = 0; i < some_var.length - 1; i++){
    if (some_var[i] <= compare_var && compare_var < some_var[i + 1]){
        return some_var[i];
    }
}

One value of some_var is 30 and the next one is 40 and the next one is 50 and compare_var is 42.

It wouldn't return 30 even though it's less-than 42, because 42 isn't less-than 40. Which also means that it would return 40 because it's less-than 42 and 42 is less-than 50.

Edit:

As someone mentioned code translation is not exactly great for SE.so. Just to make it clear: I did try several different things in ruby. I have way more experience in javascript though, so the best way I could think of to phrase my question was to write what I needed out in javascript so that I could see how it translated into ruby. Thanks for the answers

Answer 1

I would use the neato Enumerable#each_cons(n) method :

def foo(arr, x)
  arr.each_cons(2) do |a,b|
    return a if (a <= x) && (x < b)
  end
  nil # Not found
end

foo([30,40,50], 42) # => 40

This basically creates a "sliding window" of each pair and then you can just return the first item of the pair when you find the pair that encloses the target value (x).

Answer 2

这是单线的：

some_var.select{|v| v < compare_var}.max

Answer 3

Get rid of var key word, change for loop into some_var.each , and you get a working code in Ruby.

PS. Code translation is not proper in StackOverflow