On Saturday, 19 November 2016 at 07:51:36 UTC, Is it possible to
store different generic types? wrote:
On Saturday, 19 November 2016 at 06:58:38 UTC, Era Scarecrow
wrote:
On Saturday, 19 November 2016 at 04:54:22 UTC, Xinok wrote:
On Saturday, 19 November 2016 at 03:52:02 UTC, Ryan wrote:
Why do I see double `not` operators sometimes in D code? An
example it the last post of this thread.
http://forum.dlang.org/thread/ktlpnikvdwgbvfaam...@forum.dlang.org
import core.sys.windows.windows : GetConsoleCP;
bool hasConsole = !!GetConsoleCP();
Thanks.
It's a more concise way of writing:
GetConsoleCP() != 0
You can do this in C/C++ as well (and presumably some other
languages).
Hmmm... thinking about it, it does make perfect sense. The
first ! converts it to bool, the other inverts it back to it's
positive/negative state.
Although it's a combination of logic I wouldn't have through
of unless I saw it. But testing the result on any number
(float, double or real) won't be precise and would take far
longer (and more complicated) using another method.
It's a very common practice in any language that uses
truthy/falsey, especially seen a lot in Javascript.
Generally it's not necessary unless you want to be explicit
about checking upon a bool.
Ex.
auto hasModel = !!view.model;
if (hasModel) {
...
}
Could very well just be
auto model = view.model;
if (model) {
}
It's especially difficult with numbers like you did point out and
it completely depends on languages.
Most languages have false when it's 0, null, undefined etc. and
everything else is true.
Which means -1 would be true, 0 would be false, 1 would be true,
0.000001 would be true, -0.000000001 would be true.
