Triple negative in While and If?

Using Arduino Programming Questions
#1

I found these lines in a sketch that supposedly works, and wondered what the three "!" signs were for:

while(!!!client.available() && (timeout-- > 0)){

if(!!!client.available()) {

Does it mean "really, really NOT"? Would one "!" do just as well?

Is this just to make it readable, and it's going to be optimized away anyway?

#2

That’s just redundant. One ! Would do.

Sometimes you’ll see it doubled. !! What that does is it makes any non-zero value into a 1. So the firat not makes anything non-zero into zero and anything zero into 1. The second not turns the 1 back to a zero and the zeros (that were any non-zero value) become 1.

But with three nots it’s just redundant. That doesn’t do anything useful.

#3

the double bang such as !!x really helps semantically make the type of an expression a truth value (boolean) — technically 0 or 1 indeed — but semantically false or true.

You do that when you are too lazy to write (x != 0) (if x is a number type)

The triple bang is useless as it's the same as one bang - which gives you already a truth value.

Some programmers still use the triple bang to denote their intent as sometimes it's hard to see just a ! in front of a variable and you know the optimizer will get rid of it... so they see this as a way to visibly document what they really want... (I find it lame)

#4

Thanks for the clarifications. I think I'll take them back to one.

#5

One way to make a single ! visible is to put a space after it:

if (! client_available() && timeout-- > 0)

Ingeneralmorewhitespaceismorereadable.

#6

Indeed - or to use not instead of !

#7