weird empty string

[Stanislav Blinov via Digitalmars-d]

On Saturday, 13 May 2017 at 00:36:55 UTC, mogu wrote:
> ```d
> if (null)
>     "1".writeln;
> if ("")
>     "2".writeln;
> if ("" == null)
>     "3".writeln;
> ```
>
> Output:
> 2
> 3
>
> How to understand this?

Boolean conversion on an array works on array's pointer, not it's 
length. So even though `"".length == 0`, `"".ptr != null`, and so 
`cast(bool)"" == true`.