Ruby on Rails

a = [1,4,5,12,9,5,3,5] class Array   def prime_numbers     self.select(&:prime?)   end end class Integer   def prime?     return if self <= 1     (2..Math.sqrt(self).ceil).none? { |i| (self % i).zero? }   end end  a.prime_numbers => [5, 5, 3, 5]

I got to solve this problem as the part of an interview process. It wont look good if I paste the whole code here. So just sharing the link to my gitbub account. Conference Track Management

These methods can be applied on Arrays, Hashes or Objects.  Here I'm just trying to illustrate the difference between count, length and size. Array#length Basically length method returns number of elements in the array. Example, suppose we have array a rr as, a rr = [1,2,3,4,5] Calling Array#length method on array will give result as, arr.length => 5 Array#size Array#size is just an alias to the Array#length method. This method executes same as that of Array#length method internally. Example, arr.size => 5 Array#count It has more functionalities than length or size. This method can be used for getting number of elements based on some condition . Unlike length/size, we can pass block or an argument to count. This can be called in three ways: Array#count => without condition, Returns number of elements in Array Array#count(n) => passing value, Returns number of elements having value n in Array Array#count{|i| i.zero?} =...