On Aug 14, 2007, at 4:42 PM, Zangief Ief wrote:

> If my number is 1111, I would like to had 0000.
> If my number is 1001, I would like to had 0110.
> If my number is 0011, I would like to had 1100.
>
> Of cours I know we can use XOR operator, but I would like to allow  
> Ruby
> to do it more simply, just by using a function as simple as  
> possible. I
> a sure this kind of function is yet setup in Ruby, but I don't know  
> what
> is his name.

A solution:

   irb(main):003:0> "0011".tr("01", "10")
   => "1100"

-- fxn