Ruby 函数检查一个数字是否能被 5 整除并且是偶数

def is_even?(n)
  remainder_when_divided_by_2 = n % 2

  if remainder_when_divided_by_2 == 0
    return true
  else
    return false
  end
end

def is_odd?(n)
  return ! is_even?(n)
end

puts "1 is_even? #{is_even?(1)} - is_odd? #{is_odd?(1)}"
puts "2 is_even? #{is_even?(2)} - is_odd? #{is_odd?(2)}"
puts "3 is_even? #{is_even?(3)} - is_odd? #{is_odd?(3)}"
puts "4 is_even? #{is_even?(4)} - is_odd? #{is_odd?(4)}"
puts "5 is_even? #{is_even?(5)} - is_odd? #{is_odd?(5)}"
puts "6 is_even? #{is_even?(6)} - is_odd? #{is_odd?(6)}"

def is_even_and_divisible_by_five?(n)
  remainder_when_divided_by_five = n % 5

  if (remainder_when_divided_by_five == 0) && (is_even?(n) == true)
    return true
  else
    return false
  end

end

puts "5 is_even_and_divisible_by_five? #{is_even_and_divisible_by_five?(5)}"
puts "10 is_even_and_divisible_by_five? #{is_even_and_divisible_by_five?(10)}"
puts "15 is_even_and_divisible_by_five? #{is_even_and_divisible_by_five?(15)}"
puts "20 is_even_and_divisible_by_five? #{is_even_and_divisible_by_five?(20)}"
puts "25 is_even_and_divisible_by_five? #{is_even_and_divisible_by_five?(25)}"
puts "30 is_even_and_divisible_by_five? #{is_even_and_divisible_by_five?(30)}"

问题是我没有在代码底部的 put 命令中调用 is_even_and_divisible_by_ Five 方法。我将其称为 is_even_and_divisble_by_5。然后在 is_even_and_divisble_by_ Five 方法的 if 语句中，我离开了 Is_even 的 (n) 争论。非常感谢大家！

偶数（能被二整除）和能被五整除也意味着“能被十整除”：

def is_even_and_divisible_by_five?(n)
  n % 10 == 0
end