• Andrey (4/7) Nov 09 2020 Hello,
• Imperatorn (3/10) Nov 09 2020 You can check using compiler explorer:
• Vladimirs Nordholm (5/19) Nov 09 2020 I don't understand assembly, so this does not tell me anything
• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (3/17) Nov 09 2020 Cool tool!
• Daniel =?UTF-8?B?S296w6Fr?= (10/17) Nov 09 2020 In theory
• user1234 (5/12) Nov 09 2020 It's the same. If the two are valid then you are in a function.

Andrey <saasecondbox yandex.ru> writes:

Hello,

Are here any differences in creation of dynamic array with known 
size?

 auto array = new wchar[](111);

and

 wchar[] array;
 array.length = 111;

Imperatorn <johan_forsberg_86 hotmail.com> writes:

On Monday, 9 November 2020 at 08:06:54 UTC, Andrey wrote:
 Hello,

 Are here any differences in creation of dynamic array with 
 known size?

 auto array = new wchar[](111);

 and

 wchar[] array;
 array.length = 111;


You can check using compiler explorer:
https://godbolt.org/

Vladimirs Nordholm <v vladde.net> writes:

On Monday, 9 November 2020 at 09:05:58 UTC, Imperatorn wrote:
 On Monday, 9 November 2020 at 08:06:54 UTC, Andrey wrote:
 Hello,

 Are here any differences in creation of dynamic array with 
 known size?

 auto array = new wchar[](111);

 and

 wchar[] array;
 array.length = 111;


 You can check using compiler explorer:
 https://godbolt.org/

I don't understand assembly, so this does not tell me anything 
useful.

Are there any reasons to prefer one over the other? I assume this 
is what OP is actually asking about.

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

On Monday, 9 November 2020 at 09:05:58 UTC, Imperatorn wrote:
 On Monday, 9 November 2020 at 08:06:54 UTC, Andrey wrote:
 Hello,

 Are here any differences in creation of dynamic array with 
 known size?

 auto array = new wchar[](111);

 and

 wchar[] array;
 array.length = 111;


 You can check using compiler explorer:
 https://godbolt.org/

Cool tool!

Array creation disassemble: https://godbolt.org/z/GzxWao

Daniel =?UTF-8?B?S296w6Fr?= <kozzi11 gmail.com> writes:

On Monday, 9 November 2020 at 08:06:54 UTC, Andrey wrote:
 Hello,

 Are here any differences in creation of dynamic array with 
 known size?

 auto array = new wchar[](111);

 and

 wchar[] array;
 array.length = 111;


In theory
auto array = new wchar[111]; // or new wchar[](111);
should do less work, but in practice I would guess there will be 
almost zero difference in speed.

If you need to create new dynamic array with known size you 
should prefere
auto array = new wchar[111]; // or new wchar[](111);

because it is make much more sense than create empty non 
initialized array and then set it a length

user1234 <user1234 12.de> writes:

On Monday, 9 November 2020 at 08:06:54 UTC, Andrey wrote:
 Hello,

 Are here any differences in creation of dynamic array with 
 known size?

 auto array = new wchar[](111);

 and

 wchar[] array;
 array.length = 111;


It's the same. If the two are valid then you are in a function. 
So it's an alloca for the dynamic array payload (8+8 bytes on 
x86_64) then a LengthExpression that will lead to a GC.malloc, 
and finally a memset for all the elements default values.