Ruby on Rails

def binary_search(array, value, from=0, to=nil)     to = array.count - 1 unless to     mid = (from + to) / 2     if value < array[mid]       return binary_search(array, value, from, mid - 1)     elsif value > array[mid]       return binary_search(array, value, mid + 1, to)     else       return mid     end end puts binary_search([1,2,3,4,5,7,8,9,10,12,15,16,17,18], 15)

def devide(divisor, dividend)   quotient = 0   until(dividend < divisor) do     dividend -= divisor     quotient += 1   end   quotient end puts devide(15, 100)

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?} =...