Confused about referencing in D
rikki cattermole via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Wed Jul 13 23:24:55 PDT 2016
On 14/07/2016 6:23 PM, Gorge Jingale wrote:
> I'm pretty confused why the following code doesn't work as expected.
>
> GetValue is a struct.
>
> auto value = GetValue();
> memcpy(&value, &val, Val.sizeof);
>
> But if I plug in value direct to memset it works!!
>
> memcpy(&GetValue(), &val, Val.sizeof);
>
> GetValue returns memory to stick a value in and the memcpy is copying it
> over. It is very confusing logic. Should I not expect the two cases two
> be identical?
>
> I think that the assignment in the first case is not assigning the
> reference returned by auto ref GetValue().
>
> I am expecting it to work like a pointer,
>
> void* value = &GetValue();
> memcpy(value, &val, Val.sizeof);
>
> so to speak but it works more like
>
> S value;
> value = GetValue();
> memcpy(&value, &val, Val.sizeof);
>
> which copies the data to the memory created for value and not the one
> returned by GetValue.
Please provide the definitions of GetValue and Val.
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