Udacity asked the question: done is a boolean value. What is the value of !!done? here is the answer.

by Unknown 5:58 AM 0 comments algebra boolean udacity

Booleans: where everything seems to have started.

This goes back to boolean algebra, If you say

true = true   
false = false
then

not true = false
not false = true
so that means

not (not true)  = not false = true 
not (not false) = not true  = false
which means !!done = done

you can write "not" as "!"

!true  = false
!false = true
which means

!!true  = !false = true
!!false = !true = false
so if done is a boolean: true or false, when its put in !!done it will always be done. for example:

boolean done = true;
!!done this will always be its initial value which is true