What exactly are the String literrals in D and how they work?

[jfondren]

On Sunday, 15 August 2021 at 08:56:07 UTC, rempas wrote:
> On Sunday, 15 August 2021 at 08:53:50 UTC, Tejas wrote:
>> External C libraries expect strings to be null terminated, so 
>> if you do use `.dup`, use `.toStringz` as well.
>
> Yeah, yeah I got that. My question is, if I should avoid 
> `cast(char*)` and use `.toStringz` while both do the exact same 
> thing?

They don't do the same thing. toStringz always copies, always 
GC-allocates, and always NUL-terminates. `cast(char*)` only does 
what you want in the case that you're applying it a string 
literal. But in that case you shouldn't cast, you should just

```d
const char* s = "John";
```

If you need cast cast the const away to work with a C API, doing 
that separately, at the point of the call to the C function, 
makes it clearer what you're doing and what the risks are there 
(does the C function modify the string? If so this will segfault).