• Cecil Ward (19/19) Jul 08 2023 I have a dynamic array of dstrings and I’m spending dstrings to
• Cecil Ward (2/8) Jul 08 2023 s/spending/appending/
• FeepingCreature (5/14) Jul 08 2023 You can append an element to an array. You can also append an
• H. S. Teoh (8/13) Jul 08 2023 Unlike C/C++, the D runtime always ensures that things are initialized
• Cecil Ward (3/16) Jul 09 2023 Many thanks, it might give me a slightly better result just doing

Cecil Ward <cecil cecilward.com> writes:

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?

Cecil Ward <cecil cecilward.com> writes:

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/

FeepingCreature <feepingcreature gmail.com> writes:

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 ?

 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?

You can append an element to an array. You can also append an 
array to an array. Because [] can be an array of any type, the 
compiler guesses that it's an empty `string[]` array and appends 
it to no effect.

"H. S. Teoh" <hsteoh qfbox.info> writes:

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

Cecil Ward <cecil cecilward.com> writes:

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;