On Friday, 9 June 2023 at 15:07:54 UTC, Murloc wrote:
On Friday, 9 June 2023 at 12:56:20 UTC, Cecil Ward wrote:
On Friday, 9 June 2023 at 11:24:38 UTC, Murloc wrote:
If you have four ubyte variables in a struct and then
an array of them, then you are getting optimal memory usage.
Is this some kind of property? Where can I read more about this?
Yes, a classsic resource is
http://www.catb.org/esr/structure-packing/
So you can optimize memory usage by using arrays of things
smaller than `int` if these are enough for your purposes,
It's not for arrays, it's also for members
```d
struct S1
{
ubyte a; // offs 0
ulong b; // offs 8
ubyte c; // offs 16
}
struct S2
{
ubyte a; // offs 0
ubyte c; // offs 1
ulong b; // offs 8
}
static assert(S1.sizeof > S2.sizeof); // 24 VS 16
```
this is because you cant do unaligned reads for `b`, but you can
for `a` and `c`.
but what about using these instead of single variables, for
example as an iterator in a loop, if range of such a data type
is enough for me? Is there any advantages on doing that?
Not really the loop variable takes a marginal part of the stack
space in the current function. You can just use `auto` and let
the compiler choose the best type.
