This syntax regarding null checking baffles me

[kdevel]

On Thursday, 7 January 2021 at 22:42:40 UTC, Jonathan M Davis 
wrote:

[...]

> That and using ! is more consistent with what the C family of 
> languages typically does. C-derived languages don't typically 
> try to make sentences like "is not" would do. Having is and !is 
> is also more consistent with == and !=. "is not" wouldn't 
> really fit the rest of the language.

Idiomatic C is of course [1]

    char *p = ...
    if (p) ...

This form seems to be applicable for pointers in D, too. And also
for class variables

    class C { ...
    C c;

I wonder if there is a difference between

    if (c)

and

    if (c ! is null).

[1] 
https://stackoverflow.com/questions/3825668/checking-for-null-pointer-in-c-c/3825704#3825704