This program finds if a number is a happy number or not.

happy_number.rb

#this function squares a number
def square(number)
  number**2
end

#this function breaks a number into its subsequent array
def break_number_to_arr(number)
  return [0] if number.zero?
  return_arr=[]
  while number>0
    number,item = number.divmod 10
    return_arr.unshift item
  end
  return_arr
end

#this function tries to find if an number is happy number
def is_happy_number(number)
  #this array stores the number obtained in each steps
  visited_arr=[]
  while(number!=1)
    puts "INFO: Checking for #{number}"
    temp_sum=0
    break_number_to_arr(number).each { |item| temp_sum+=square(item) }
    number = temp_sum

    #check if number is already visited
    if(visited_arr.include? number)
      return false
    else
      #add number to visited list
      visited_arr << number
    end
      
  end
  return true
end

#main program begins here
puts "Enter any number:"

begin
  #typecast to integer
  input =Integer(gets.chomp)

  #check if input number is a happy number
  if(is_happy_number(input))
    puts "#{input} is a happy Number. YAHOO"
  else
    puts "#{input} is not a happy Number."
  end

#if error
rescue
  puts "Please enter a valid Number."

end