Convert positive integer to negative integer

Question

  def negate_amount
    amount = model.amount.to_s
    ("-" + amount).to_i
  end

is there a better way to turn positive integer to negative?

The code above works, but is there a ruby or rails function for that? Without doing math operations?

Answer 1

You can just use the unary - operator:

def negate_amount
    -model.amount
end

Answer 2

Similar question to How do I convert a positive number to negative?. But in summary, if you are always expecting a negative answer you could simply say

def negate_amount
    amount = -(model.abs)
end

Otherwise, if you simply want the function to return a negative of the integer : assuming negating a negative number returns a positive number, then you would use

def negate_amount
    amount = -(model)
end