Re: is the array literal in a loop stack or heap allocated?
On Wednesday, 11 October 2023 at 02:54:53 UTC, mw wrote:
Hi,
I want to confirm: in the following loop, is the array literal
`a` vs. `b` stack or heap allocated? and how many times?
void main() {
int[2] a;
int[] b;
int i;
While(++i <=100) {
a = [i, i+1]; // array literal
b = [i, i+1];
}
}
Thanks.
profile=gc
Re: is the array literal in a loop stack or heap allocated?
On Wednesday, 11 October 2023 at 03:15:30 UTC, H. S. Teoh wrote:
On Wed, Oct 11, 2023 at 02:54:53AM +, mw via
Digitalmars-d-learn wrote:
Hi,
I want to confirm: in the following loop, is the array literal
`a` vs. `b` stack or heap allocated? and how many times?
void main() {
int[2] a;
This is stack-allocated. Once per call to the function.
int[] b;
This is an empty slice. It can refer to either stack or heap
memory, depending on what's assigned to it.
int i;
While(++i <=100) {
a = [i, i+1]; // array literal
`a` is overwritten in-place once per loop.
How about the temporary array literal on the right hand side?
It's stack / heap allocated? Or it's not in the language
specification, but up to the (optimizing) compiler to decide?
b = [i, i+1];
[...]
A new array consisting of 2 elements is allocated, once per
loop, and assigned to b each time. Any arrays from previous
iterations will be collected by the GC eventually.
T
Re: is the array literal in a loop stack or heap allocated?
On Wednesday, 11 October 2023 at 02:54:53 UTC, mw wrote:
Hi,
I want to confirm: in the following loop, is the array literal
`a` vs. `b` stack or heap allocated? and how many times?
void main() {
int[2] a;
int[] b;
int i;
While(++i <=100) {
a = [i, i+1]; // array literal
b = [i, i+1];
}
}
Thanks.
a is a static array, therefore it won't allocate any, it's a
memcpy
b will be heap allocated, and it'll do an allocate at each
iteration
```D
void test_b()
{
int[] a;
int i;
while (++i <= 100)
{
a = [i, i + 1];
printf("%p\n", a.ptr);
}
}
```
You can run this, and it'll print a different address each time
If you add `[]` it'll do range based copy (memcpy), but since the
array is not initialized, it has a length of 0, so you only need
to allocate once (either with GC or with malloc)
```D
void test_b()
{
int[] a;
int i;
a.length = 2; // initialize the heap allocated array here
// or with malloc:
// auto ptr = malloc(int.sizeof * 2);
// a = cast(int[]) ptr[0 .. int.sizeof * 2];
while (++i <= 100)
{
a[] = [i, i + 1];
printf("%p\n", a.ptr);
}
}
```
Otherwise you'd get: ``core.exception.RangeError@onlineapp.d(18):
Range violation``
I don't use D with the GC, so my memory about it is probably
foggy, but i'm pretty sure what i said is right, please anyone
correct me if i'm wrong
Re: is the array literal in a loop stack or heap allocated?
On Wed, Oct 11, 2023 at 02:54:53AM +, mw via Digitalmars-d-learn wrote:
> Hi,
>
> I want to confirm: in the following loop, is the array literal `a` vs.
> `b` stack or heap allocated? and how many times?
>
> void main() {
>
> int[2] a;
This is stack-allocated. Once per call to the function.
> int[] b;
This is an empty slice. It can refer to either stack or heap memory,
depending on what's assigned to it.
> int i;
> While(++i <=100) {
>
> a = [i, i+1]; // array literal
`a` is overwritten in-place once per loop.
> b = [i, i+1];
[...]
A new array consisting of 2 elements is allocated, once per loop, and
assigned to b each time. Any arrays from previous iterations will be
collected by the GC eventually.
T
--
They pretend to pay us, and we pretend to work. -- Russian saying
is the array literal in a loop stack or heap allocated?
Hi,
I want to confirm: in the following loop, is the array literal
`a` vs. `b` stack or heap allocated? and how many times?
void main() {
int[2] a;
int[] b;
int i;
While(++i <=100) {
a = [i, i+1]; // array literal
b = [i, i+1];
}
}
Thanks.
Re: Define a new custom operator in D Language.
On Monday, 2 October 2023 at 18:34:13 UTC, BoQsc wrote: --- **This might lead to less gaps between math formulas and the implementation.** Or at the very least would allow to define a formula in the source code for further implementation and introduce some consistency. You could write a parser with pegged https://code.dlang.org/packages/pegged Could probably support unicode math symbols.
Re: Need help with 128bit integer ucent boolfilter
On Friday, 6 October 2023 at 13:44:14 UTC, d007 wrote: I am search for a fast 128bit integer ucent boolfilter, used for server side duplicate request filter. Is 128bit boolfilter a doable thing? or it will not work or will be much more slow compare to 64 bit solution? Can you describe or give a reference to what you mean by bool filter?
Re: How to use ".stringof" to get the value of a variable and not the name of the variable (identifier) itself?
On Tuesday, 10 October 2023 at 13:55:44 UTC, rempas wrote: On Tuesday, 10 October 2023 at 11:46:38 UTC, Hipreme wrote: My engine has its own implementation of toString(long), which does not have dependency with the C runtime: https://github.com/MrcSnm/HipremeEngine/blob/master/modules/util/source/hip/util/conv.d#L180C1-L208C2 I have reimplemented the entire conv module since it is one of mostly used module and it pulled down a lot of things, so, with my util module I was able to make my program much smaller too. Thank you for the idea! However, your code used Phobos which I don't want to use so it will not do. Which part uses Phobos? The linked function compiles without importing anything.
Re: How to use ".stringof" to get the value of a variable and not the name of the variable (identifier) itself?
On Tuesday, 10 October 2023 at 11:46:38 UTC, Hipreme wrote: My engine has its own implementation of toString(long), which does not have dependency with the C runtime: https://github.com/MrcSnm/HipremeEngine/blob/master/modules/util/source/hip/util/conv.d#L180C1-L208C2 I have reimplemented the entire conv module since it is one of mostly used module and it pulled down a lot of things, so, with my util module I was able to make my program much smaller too. Thank you for the idea! However, your code used Phobos which I don't want to use so it will not do.
Re: How to use ".stringof" to get the value of a variable and not the name of the variable (identifier) itself?
On Tuesday, 10 October 2023 at 11:45:25 UTC, Dennis wrote:
The result of `.stringof` is implementation defined, it can be
used for debugging but don't make your program's semantics
depend on the output of it.
...
...
...That being said, this trick can be used to convert an
integer to string at compile time:
```D
enum itoa(int i) = i.stringof;
static foreach(i; 0 .. 10) {
mixin(create_fn!(itoa!i));
}
```
Technically not reliable, but I don't expect integers to ever
get printed differently than a string of base 10 digits.
Thank you! It is great and works great. I will however use the
example from Imperatorn as it does not use ".stringof". Have an
amazing day!
Re: How to use ".stringof" to get the value of a variable and not the name of the variable (identifier) itself?
On Tuesday, 10 October 2023 at 05:32:52 UTC, Imperatorn wrote:
If count < 10 then why not just
```d
import std;
static foreach(c; "0123456789")
{
mixin(create_fn!(c));
}
enum create_fn(char num) = `
auto function_`~ num ~`()
=> "Hello from function `~ num ~`!";
`;
void main()
{
assert(function_9() == "Hello from function 9!");
}
```
Thank you! Yeah, the most clean code wins for me, so I'll use
yours (if it's open source, lol)! Thank you and have an amazing
day!
Re: How to use ".stringof" to get the value of a variable and not the name of the variable (identifier) itself?
On Monday, 9 October 2023 at 22:49:11 UTC, Salih Dincer wrote:
Great masters generally warn to stay away from stringof. Please
do not use it as much as possible. The following code snippet
will be useful to you:
```d
alias CN = __traits(allMembers, CardinalNumbers);
static foreach(i; CN)
{
mixin(create_fn!(i[1]));
}
enum create_fn(char num) = `
auto function_`~ num ~`()
=> "Hello from function `~ num ~`!";
`;
enum CardinalNumbers
{
n0, n1, n2, n3, n4, n5, n6, n7, n8, n9
}
void main()
{
assert(function_9() == "Hello from function 9!");
}
```
SDB@79
Thank you so much! This will do the trick. Have a beautiful day!
Re: How to use ".stringof" to get the value of a variable and not the name of the variable (identifier) itself?
On Monday, 9 October 2023 at 18:25:15 UTC, rempas wrote: On Monday, 9 October 2023 at 17:42:48 UTC, Imperatorn wrote: You could just add your own int to string I guess? That will be a good idea! I'll do it in the future if that is the case, as it's not important, and I want to finish my job. Thank you and have a great day! My engine has its own implementation of toString(long), which does not have dependency with the C runtime: https://github.com/MrcSnm/HipremeEngine/blob/master/modules/util/source/hip/util/conv.d#L180C1-L208C2 I have reimplemented the entire conv module since it is one of mostly used module and it pulled down a lot of things, so, with my util module I was able to make my program much smaller too.
Re: How to use ".stringof" to get the value of a variable and not the name of the variable (identifier) itself?
On Monday, 9 October 2023 at 16:33:32 UTC, rempas wrote:
However, in my example, "stringof" returns the character "i"
itself and turns that into a string instead of getting its
actual value (number).
The result of `.stringof` is implementation defined, it can be
used for debugging but don't make your program's semantics depend
on the output of it.
...
...
...That being said, this trick can be used to convert an integer
to string at compile time:
```D
enum itoa(int i) = i.stringof;
static foreach(i; 0 .. 10) {
mixin(create_fn!(itoa!i));
}
```
Technically not reliable, but I don't expect integers to ever get
printed differently than a string of base 10 digits.
