Re: New vs length on dymamic array
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
Re: New vs length on dymamic array
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.
Re: New vs length on dymamic array
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
Re: New vs length on dymamic array
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.
Re: New vs length on dymamic array
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/
New vs length on dymamic array
Hello, Are here any differences in creation of dynamic array with known size? auto array = new wchar[](111); and wchar[] array; array.length = 111;
