I have a dynamic array of dstrings and I’m spending dstrings to it. At one point I need to append a zero-length string just to increase the length of the array by one but I can’t have a slot containing garbage. I thought about ++arr.length - would that work, while giving me valid contents to the final slot ?

What I first did was
   arr ~= [];

This gave no errors but it doesn’t increase the array length, so it seems. Is that a bug ? Or is it supposed to do that?

Then I tried
    arr ~= ""d;
and that did work. Is there anything more efficient that I could do instead?

I actually have an alias for the type of the strings so that they can be either dstrings or wstrings with just a recompilation. How should I then generate a zero-length string that has th correct type of dstring or wstring as I am stuck with the ‘d’-suffix on the end of the ""d at the moment. Can I just cast ? Not a reinterpret cast, but a proper value conversion?

On Saturday, 8 July 2023 at 17:15:26 UTC, Cecil Ward wrote:
> I have a dynamic array of dstrings and I’m spending dstrings to it. At one point I need to append a zero-length string just to increase the length of the array by one but I can’t have a slot containing garbage. I thought about ++arr.length - would that work, while giving me valid contents to the final slot ?
>
> [...]

s/spending/appending/

On Sat, Jul 08, 2023 at 05:15:26PM +0000, Cecil Ward via Digitalmars-d-learn wrote:
> I have a dynamic array of dstrings and I’m spending dstrings to it. At one point I need to append a zero-length string just to increase the length of the array by one but I can’t have a slot containing garbage. I thought about ++arr.length - would that work, while giving me valid contents to the final slot ?

Unlike C/C++, the D runtime always ensures that things are initialized unless you explicitly tell it not to (via void-initialization). So ++arr.length will work; the new element will be initialized to dstring.init (which is the empty string).


T

-- 
If Java had true garbage collection, most programs would delete themselves upon execution. -- Robert Sewell

On Saturday, 8 July 2023 at 20:01:08 UTC, H. S. Teoh wrote:
> On Sat, Jul 08, 2023 at 05:15:26PM +0000, Cecil Ward via Digitalmars-d-learn wrote:
>> I have a dynamic array of dstrings and I’m spending dstrings to it. At one point I need to append a zero-length string just to increase the length of the array by one but I can’t have a slot containing garbage. I thought about ++arr.length - would that work, while giving me valid contents to the final slot ?
>
> Unlike C/C++, the D runtime always ensures that things are initialized unless you explicitly tell it not to (via void-initialization). So ++arr.length will work; the new element will be initialized to dstring.init (which is the empty string).
>
>
> T

Many thanks, it might give me a slightly better result just doing ++arr.length;