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From: Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups: comp.lang.javascript
Subject: Re: Logic problem, i always had problem translate until statements into while
Date: Thu, 26 Jan 2017 23:06:18 +0000
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jonas.thornvall@gmail.com writes:

> Den torsdag 26 januari 2017 kl. 22:24:32 UTC+1 skrev jonas.t...@gmail.com:
>> Den torsdag 26 januari 2017 kl. 21:29:05 UTC+1 skrev Ben Bacarisse:
>> > jonas.thornvall@gmail.com writes:
>> > 
>> > > do until (regular == true && connected == false )
>> > >
>> > > I honestly feel a bit lost, because i think they are so easy to code
>> > > using do until.
>> > 
>> > What as the initial values of 'regular' and 'connected'?
>> > 
>> > > So how should i think about it?
>> > 
>> > Provided the initial value of the resulting while condition is true you
>> > just need to invert it:
>> > 
>> >   while (!(regular == true && connected == false)) ...
>> > 
>> > You can use De Morgan's laws to simplify that if you like:
>> > 
>> >   !(A && B) <=> !A || !B
>> >   !(A || B) <=> !A && !B
>> > 
>> > in your case
>> > 
>> >      !(regular == true && connected == false)
>> >   => !(regular == true) || !(connected == false) 
>> >   => regular != true || connected != false
>> > 
>> > which I'd just write as
>> > 
>> >   while (!regular || connected) ...
>> > 
>> > Often, the use of do ... until is simply an error (while is needed more
>> > often in algorithms than do...until).  In those cases there is no need
>> > for the loop to execute at least once and you don't need to check that
>> > '!regular || connected' is initially true.
>> > 
>> > -- 
>> > Ben.
>> 
>> Unfortunately they are both false,

Why is that unfortunate?  If they are both initially false your
do...until can be written as a while with the condition negated.

<snip>
-- 
Ben.