Re: Challenge Tuples
On Friday, 26 April 2024 at 13:25:34 UTC, Salih Dincer wrote:
...
Very nice, for your first example I need to think a bit because
I'm bit rusty in C#, but I think it will not be as easier as D
version.
For the bonus part:
private static void Main(string[] args){
var a = (1,2,3,(1,3),5);
var t = a as ITuple;
var xx = new List();
for(var i=0;i if(t[i].GetType() ==
typeof(System.ValueTuple)){
var t2 = (t[i] as ITuple);
var s = 0;
for(var j=0;jAgain I'm rusty in C#... but so far yes it's more verbose than
the D version.
Matheus.
Re: How to make fields inaccessible (unreadable and unachangeable) outside of the structure?
On Saturday, 30 March 2024 at 02:11:25 UTC, zjh wrote: On Friday, 29 March 2024 at 22:50:53 UTC, curiousprogramma08 wrote: you can use openD. Wait a minute, they already added this modification into their language? Interesting! Matheus.
Re: How to make fields inaccessible (unreadable and unachangeable) outside of the structure?
On Friday, 29 March 2024 at 22:50:53 UTC, curiousprogramma08 wrote: ... If I'm not mistaken, like in classes "private" is module based: https://wiki.dlang.org/Access_specifiers_and_visibility Matheus.
Re: Why is this code slow?
On Sunday, 24 March 2024 at 19:31:19 UTC, Csaba wrote: ... Here are the results: C: 0.04s Python: 0.33s D: 0.73s ... I think a few things can be going on, but one way to go is trying using optimization flags like "-O2", and run again. But anyway, looking through Assembly generated: C: https://godbolt.org/z/45Kn1W93b D: https://godbolt.org/z/Ghr3fqaTW The Leibniz's function is very close each other, except for one thing, the "pow" function on D side. It's a template, maybe you should start from there, in fact I'd try the pow from C to see what happens. Matheus.
Re: Alguien me dice como podria conectarme a una base de datos en SQL server?
On Thursday, 14 March 2024 at 17:08:17 UTC, dany wrote: ... queria conectarme a SQLserver :'( You will need an ODBC driver (Bindings): https://code.dlang.org/packages/arsd-official%3Amssql Matheus.
Re: The difference between the dates in years
On Saturday, 10 February 2024 at 22:11:48 UTC, Brad Roberts wrote: Back when I was doing lots of software developer interviews, one of my frequent questions involved date math. This wasn't because it's difficult from a coding standpoint, but that it's NOT a coding problem. The key part of the question is realization that it's a requirements question. The thing that makes dates complicated is defining what the question actually is. The topic _seems_ like it should be simple, but the deeper you dig the more you realize it's anything but simple. Interesting but I have a doubt, they (Interviewees) should do the test with already existing Date Functions of given language or write new ones? Matheus.
Re: The difference between the dates in years
On Saturday, 10 February 2024 at 19:16:35 UTC, Alexander Zhirov
wrote:
...
Maybe this will help: I think if you will divide it can't be 365,
but 365.242199.
About your code: I having tested fully, but I found a few
problems and I wrote (Again without further tests) as below:
import std;
int getDiffYears(string date) {
auto currentDate = cast(Date)Clock.currTime();
auto startDate = Date.fromISOExtString(date);
auto currentDay = currentDate.dayOfYear;
auto startDay = startDate.dayOfYear;
auto currentMonth = currentDate.month;
auto startMonth = startDate.month;
auto diffDays = currentDate - startDate;
auto diffYears = diffDays.total!"days"().to!int / 365;
return currentMonth >= startMonth && currentDay >= startDay ?
diffYears : diffYears - 1;
}
int getDiffYears2(string date) {
auto now = cast(Date)Clock.currTime();
auto from = Date.fromISOExtString(date);
auto dy = now.year-from.year;
auto dm = (from.month-now.month);
auto dd = (dm == 0 && from.day>now.day);
return dy - 1 * (dm > 0 || dd);
}
void main(){
writeln("2001-02-09 is ", getDiffYears("2001-02-09"));
writeln("2001-02-10 is ", getDiffYears("2001-02-10"));
writeln("2001-02-11 is ", getDiffYears("2001-02-11"));
writeln("2001-03-01 is ", getDiffYears("2001-03-01"));
writeln("");
writeln("2001-02-09 is ", getDiffYears2("2001-02-09"));
writeln("2001-02-10 is ", getDiffYears2("2001-02-10"));
writeln("2001-02-11 is ", getDiffYears2("2001-02-11"));
writeln("2001-03-01 is ", getDiffYears2("2001-03-01"));
}
Output:
2001-02-09 is 23
2001-02-10 is 23
2001-02-11 is 22
2001-03-01 is 21
2001-02-09 is 23
2001-02-10 is 23
2001-02-11 is 22
2001-03-01 is 22
Matheus.
Re: Would you recommend TDPL today?
On Tuesday, 16 January 2024 at 02:25:32 UTC, matheus wrote: ... I'll reply to myself but I just would like to say thanks to Jonathan M Davis and Mike Shah. I started with TDPL but I'll fill my knowledge with the other suggestions you gave me. Thanks again, Matheus.
Would you recommend TDPL today?
Hi, I'm mostly a lurker in these Forums but sometimes I post here and there, my first language was C and I still use today together with my own library (A Helper) which is like a poor version of STB (https://github.com/nothings/stb). I usually use D language sometimes as C on steroids, using AA and GC and some other features, but I never entered in this realm very deeply. I always wanted to dive in and I always postponed, but I decided to go a littler deeper, and I thought about going with The D Programming Language, but as I see it is from 2010, and I wonder if is it a good resource to go currently? I don't care about the age of the book, since I learned C in late 90's with Kernighan and Ritchie "The C Programming Language", but at time C was "stable", now I think D maybe has evolved much more in these 14 years, so I'm a bit on the fence. Any thoughts or recommendations? Thanks, Matheus.
Re: Doubt about Struct and members
On Monday, 8 January 2024 at 17:56:19 UTC, H. S. Teoh wrote: ... It's not recommended to use initializers to initialize mutable array-valued members, because it probably does not do what you think it does. What the above code does is to store the array ["ABC"] somewhere in the program's pre-initialized data segment and set s to point to that by default. It does NOT allocated a new array literal every time you create a new instance of S; every instance of S will *share* the same array value unless you reassign it. As such, altering the contents array may cause the new contents to show up in other instances of S. This behaviour is generally harmless if your array is immutable. In fact, it saves space in your executable by reusing the same data for multiple instances of s. It also avoids repeated GC allocations at runtime. ... First of all thanks for replying, Yes I understood the behavior since I even looked the code generated: https://godbolt.org/z/xnsbern9f =] Maybe my question was poorly written (I'm ESL), but you answered in the other Topic: "(Whether the current behaviour should be changed is up for debate, though. This definitely isn't the first time users have run into this. In fact just today somebody else asked the same question on D.learn. So it's definitely in the territory of "does not do the expected thing", which is an indication that the default behaviour was poorly chosen.)" I was in doubt about if this was intended or not... and it seems the case. I'm not saying it is wrong by any means, I just found a bit tricky based on the two ways it could change the value pointed by the address and/or the address of the member itself. Again thanks, Matheus.
Doubt about Struct and members
Hi,
I was doing some tests and this code:
import std;
struct S{
string[] s = ["ABC"];
int i = 123;
}
void foo(bool b, string str){
S t1;
writeln("t1.s: ", t1.s, ", t1.s.ptr: ", t1.s.ptr, " t1.i: ",
t1.i);
if(b){
t1.s[0] = str;
}else{
t1.s = [str];
}
t1.i = 456;
S t2;
writeln("t1.s: ", t1.s, ", t1.s.ptr: ", t1.s.ptr, " t1.i: ",
t1.i);
writeln("t2.s: ", t2.s, ", t2.s.ptr: ", t2.s.ptr, " t2.i: ",
t2.i);
writeln("");
}
void main(){
foo(false, "DEF");
foo(true, "DEF");
foo(false, "XYZ");
}
Outputs:
t1.s: ["ABC"], t1.s.ptr: 56421C6D7010 t1.i: 123
t1.s: ["DEF"], t1.s.ptr: 7EFC725E6000 t1.i: 456
t2.s: ["ABC"], t2.s.ptr: 56421C6D7010 t2.i: 123
t1.s: ["ABC"], t1.s.ptr: 56421C6D7010 t1.i: 123
t1.s: ["DEF"], t1.s.ptr: 56421C6D7010 t1.i: 456
t2.s: ["DEF"], t2.s.ptr: 56421C6D7010 t2.i: 123
t1.s: ["DEF"], t1.s.ptr: 56421C6D7010 t1.i: 123
t1.s: ["XYZ"], t1.s.ptr: 7EFC725E6020 t1.i: 456
t2.s: ["DEF"], t2.s.ptr: 56421C6D7010 t2.i: 123
As you can see:
t1.s = [str];
Just changed generated a new address only for t1.s, on the other
hand:
t1.s[0] = str;
Changed the value pointed by S.s entirely (The other "instance"
t2 since points to the same address now has the new value too).
Is this intended?
Matheus.
Re: Advent of Code 2023
On Saturday, 2 December 2023 at 13:33:33 UTC, Johannes Miesenhardt wrote: On Friday, 1 December 2023 at 01:01:31 UTC, Siarhei Siamashka wrote: Advent of Code 2023 starts in a few hours from now. I suggest to discuss D language solutions here. But to avoid spoilers, it's best to do this with a 24h delay after each puzzle is published. Day 1 solution ```d version = Part2; import std.stdio; import std.algorithm; import std.array; import std.format; import std.conv; import std.string; ... Why do you do multiple imports instead of one import std;? I means is there any difference in CT? Matheus.
Re: Weird bug in std.logger? Possible memory corruption
On Wednesday, 1 November 2023 at 17:26:42 UTC, Christian Köstlin wrote: ... It's really weird: https://run.dlang.io/is/fIBR2n Interesting because I wrote a similar test as you did. And that increment (Or lack of) called my attention, If I can I'll try and take a look at that (std.logger) info() Implementation later after work. Matheus.
Re: Weird bug in std.logger? Possible memory corruption
On Tuesday, 31 October 2023 at 21:19:34 UTC, Arafel wrote:
...
Assigning the value to a variable works as expected:
```d
import std.logger : info;
void main() {
auto s = foo();
info(s);
}
auto foo() {
info("In foo");
return "Hello, world.";
}
```
...
Unless you do:
string s;
info(s=foo());
I think this is a bug, or at least very weird behavior.
Matheus.
Re: Want to try out string interpolation in D?
On Friday, 20 October 2023 at 16:41:40 UTC, Imperatorn wrote:
Here's a script to get you started
...
Now try string interpolation:
```d
import std.stdio;
void main()
{
string name = "Johan";
int age = 37;
int iq = 8001;
int coffees = 1000;
writeln(i"Your name is $name and you're $age years old");
writeln(i"You drink $coffees cups a day and it gives you
$(coffees + iq) IQ");
}
```
Output:
```
Your name is Johan and you're 37 years old
You drink 1000 cups a day and it gives you 9001 IQ
```
First of all thanks for writing this.
Well this seems pretty nice... What DIP number is this? - I'd
like to read why it was rejected.
Matheus.
Re: Indenting standards religions K, whitesmiths etc
On Wednesday, 31 May 2023 at 16:24:38 UTC, Cecil Ward wrote:
...
So my question: would I get lynched for the following? (below)
...
I don't know nothing about all this but looking your example
code, I write and I'd prefer to read something like this (Editing
your own code):
pure nothrow etc T foo(T, T2)(in T param x,in T2 param y)
if (template-qualification-whatever) in {
static assert(…);
}
out (ret){
…
assert(test ret);
}do{
blah
if (test) {
if-body
…
}
back to main block
…
…
}
Matheus.
Re: Any working REPL program on windows? DREPL doesn't compile
On Thursday, 23 March 2023 at 09:39:40 UTC, John Xu wrote: Anybody know any working REPL program? I failed to find a working one. https://github.com/dlang-community/drepl can't compile on my Windows 10, dub reports: ... According to their Readme: Supported OS Works on any OS with full shared library support by DMD (currently linux, OSX, and FreeBSD). Matheus.
Re: Need some technical help an object oriented wrapper I am creating for bindbc.sfml
On Tuesday, 24 January 2023 at 03:42:34 UTC, thebluepandabear wrote: ... if not please tell me and I will remove this... How you would do that? Matheus.
Re: Coding Challenges - Dlang or Generic
On Wednesday, 18 January 2023 at 04:51:11 UTC, Salih Dincer wrote: On Tuesday, 17 January 2023 at 21:50:06 UTC, matheus wrote: Have you compared the timings between this way (With ranges) and a normal way (Without ranges)? Of course it is possible to speed it up. However, even as it is, it is enough to see the power of intervals. I would argue that you'll get fast results even with DMD Compiler! ```d ... Well I'll need to check this, because your version is slightly different than mine and this one (https://github.com/quickfur/dcal/blob/master/dcal.d), It prints only one column. I'll change mine to do this and compare, I can't do this right now because I'm at work. But unfortunately I can't use xTest = 1200 on these online compilers, only 10 or they will stop. Could you please run your version vs mine (Changing to print one column, line 70: draw_year(2023,1); ) and tell us the result? Matheus.
Re: Coding Challenges - Dlang or Generic
On Wednesday, 18 January 2023 at 01:05:58 UTC, Siarhei Siamashka wrote: On Tuesday, 17 January 2023 at 23:27:03 UTC, matheus wrote: I ran in two sites: https://onecompiler.com/d and then https://godbolt.org/, with the latter I set LDC with -O2. My version (Source in the end) ran about 2x faster than the version with ranges. Well, the use of ranges is not the only difference. ... What are the other differences? Just remember what I said above: I ran my version against the one with ranges (From: https://github.com/quickfur/dcal/blob/master/dcal.d), and I modified to just print the calendar for some year. Again I ran both versions with/without ranges only generating and printing the months. Matheus.
Re: Coding Challenges - Dlang or Generic
On Tuesday, 17 January 2023 at 23:08:19 UTC, Siarhei Siamashka
wrote:
On Tuesday, 17 January 2023 at 21:50:06 UTC, matheus wrote:
Question: Have you compared the timings between this way (With
ranges) and a normal way (Without ranges)?
If you are intensively using ranges, UFCS or the other
convenient high level language features, then the compiler
choice does matter a lot. And only LDC compiler is able to
produce fast binaries from such source code.
...
I ran in two sites: https://onecompiler.com/d and then
https://godbolt.org/, with the latter I set LDC with -O2.
My version (Source in the end) ran about 2x faster than the
version with ranges.
...
I'm using D Online Compiler from different platforms but
unfortunately I can't loop too much because they don't accept,
but anyway a normal version runs almost twice faster than this
version (With ranges).
Can you try to run the following diagnostics program on this D
Online Compiler platform?
https://gist.github.com/ssvb/5c926ed9bc755900fdaac3b71a0f7cfd
https://onecompiler.com/d/3yv7t9ap9
Gives me:
HelloWorld.d(43): Error: undefined identifier `volatileStore`
HelloWorld.d(44): Error: undefined identifier `volatileLoad`
If you like I could send or post here a version without ranges
to try out.
Please post it. This is interesting.
Like I said above I ran my version against the one with ranges
(From: https://github.com/quickfur/dcal/blob/master/dcal.d), and
I modified to just print the calendar for some year.
With godbolt.org LDC -O2 my version ran 2x faster, and here is
the source:
import std.stdio, std.string, std.conv, std.range, std.datetime;
import std.datetime.stopwatch : benchmark, StopWatch;
void draw_months(int year ,int month, int columns){
int i;
if(month>12){return;}
auto columspace = " ".replicate(columns);
write("\n");
for(i=0;i12){break;}
write(" " ~ " ".replicate(11*(i>0)) ~
columspace,capitalize(to!string(Date(year,month+i,1).month)));
}
write("\n");
auto m = new string[][](columns);
for(int j=0;j12){return;}
for(i=1;i<8;++i){
write(to!string(Date(1899,1,i).dayOfWeek)[0..2], " ");
}
int c = DW[to!string(Date(year,month+j,1).dayOfWeek)];
auto dm = Date(2023,month+j,1).daysInMonth;
for(i=0;i
Re: Coding Challenges - Dlang or Generic
On Friday, 13 January 2023 at 21:12:17 UTC, Salih Dincer wrote: On Friday, 13 January 2023 at 18:59:01 UTC, matheus wrote: Unfortunately it's not working for me Yeah, it was an old development version. I also implemented another version the same day: * [Nested Class](https://forum.dlang.org/thread/vkjhkftvyprsivozy...@forum.dlang.org) * [Only One Struct](https://forum.dlang.org/post/thxvuddjimgswalzo...@forum.dlang.org) SDB@79 Sory... No problem. =] Question: Have you compared the timings between this way (With ranges) and a normal way (Without ranges)? I'm using D Online Compiler from different platforms but unfortunately I can't loop too much because they don't accept, but anyway a normal version runs almost twice faster than this version (With ranges). If you like I could send or post here a version without ranges to try out. Matheus.
Re: How to access private variable of outer class from an inner struct
On Sunday, 15 January 2023 at 12:44:51 UTC, thebluepandabear
wrote:
...
How will the variable `outer` become the reference to the
current `X` object (if that makes sense?). Does the compiler do
it automatically?
I think you'll need to do this:
class X {
private int num;
struct Y {
X outer;
int fun() { return outer.num; }
}
Y y;
this(){
y = Y(this);
}
}
void main(){
import std.stdio : writeln;
auto x = new X();
x.num = 10;
writeln(x.num);
writeln(x.y.fun());
}
Prints:
10
10
Matheus.
Re: Coding Challenges - Dlang or Generic
On Thursday, 12 January 2023 at 19:06:49 UTC, Salih Dincer wrote: ... Now, I wrote a nested class using range and copying from Matheus' code. Of course not as comprehensive as [your dcal](https://github.com/quickfur/dcal/blob/master/dcal.d). I like this one and even thought of a new challenge! ... Hi Salih, Unfortunately it's not working for me: .d(79): Error: found `End of File` when expecting `}` following compound statement So I think it's missing a "}" in main, and after I added that, it gives: .d(46): Error: undefined identifier `replicated`, did you mean template `replicate(S)(S s, size_t n) if (isDynamicArray!S)`? Matheus.
Re: Coding Challenges - Dlang or Generic
On Tuesday, 10 January 2023 at 22:10:57 UTC, Paul wrote: ... I think you must have done a blog post or tutorial or something, Teoh, because I've seen this before. Don't let this go to your head :), but I was blown away by the presentation and solution! BTW where is it posted? ITT: https://forum.dlang.org/post/tpjhr3$2ilc$1...@digitalmars.com drug007 wrote: [To clarify the situation](https://wiki.dlang.org/Component_programming_with_ranges) (H S Teoh is the author of this article) Matheus.
Re: Coding Challenges - Dlang or Generic
On Tuesday, 10 January 2023 at 11:23:15 UTC, drug007 wrote: 10.01.2023 13:57, matheus пишет: ... [To clarify the situation](https://wiki.dlang.org/Component_programming_with_ranges) (H S Teoh is the author of this article) Hmm very interesting (I'm at work and I just gave it a glimpse). But since I'm a C programmer who just play with D as hobby I would need more time to digest it. I'll try to read it later. Matheus.
Re: Coding Challenges - Dlang or Generic
On Tuesday, 10 January 2023 at 07:38:31 UTC, Salih Dincer wrote: On Tuesday, 10 January 2023 at 03:18:54 UTC, matheus wrote: ...` You don't need validDate. Because there is daysInMonth: ... That's really better. thanks for the info. Matheus.
Re: Coding Challenges - Dlang or Generic
On Tuesday, 10 January 2023 at 05:21:15 UTC, H. S. Teoh wrote: Printing it in this format is trivial, and not very interesting. The interest in the challenge is to lay it out like I posted, side-by-side,... Like I said I did it over D online compiler which unfortunately I couldn't validate the output because it "wraps" the text, and the font wasn't monospace. But It just a case of changing the loop in a way to print 3 groups of months. ... and to do so in a way that the code is clean, maintainable, and consists of reusable components. ... Talking about modularity and reusable components, I really think it depends, because if that's was really the case, then I would think of using the OS functions to move the cursor around (If console/terminal) to print a given month in some location or side by side until reach some horizontal limit (Terminal), then it could be 1 column only (Like I did), 2, 3 and maybe 4 columns if the terminal/resolution permit, and for that I would use ARSD. :] But I think this would be too much for this kind of thing writing on online compiler. ... That's where the challenge lies. To be honest when I saw your proposal, I really thought that the real challenge would be to write my own algo to handle the date, and I was pretty sure after posting above, you would say that, but not about the layout or printing in groups. =] Matheus.
Re: Coding Challenges - Dlang or Generic
On Tuesday, 10 January 2023 at 01:22:33 UTC, H. S. Teoh wrote:
...
Here's a challenge. Given an input year, for example, "2023",
write a program that outputs (for the corresponding year):
...
The layout isn't like yours, I wrote this using a D Online
compiler and I'm very sleepy right now:
import std.stdio, std.string, std.conv, std.datetime;
bool validDate(int y,int m,int d){
try{
Date(y,m,d);
return true;
}catch(Exception e){}
return false;
}
void main(){
int[string] dow;
int i, y = 2023, m = 1, d = 1;
for(i=1;i<8;++i){
dow[to!string(Date(1899,1,i).dayOfWeek)]=i;
}
for(m=1;m<13;++m){
write("\n\n\t\t",capitalize(to!string(Date(y,m,1).month)),"\n");
for(i=1;i<8;++i){
write(to!string(Date(1899,1,i).dayOfWeek)[0..2], " ");
}
writeln();
int c = dow[to!string(Date(y,m,1).dayOfWeek)];
for(i=1;i
Re: Why does this code only work with `std.conv.to` whilst not with `cast`?
On Sunday, 8 January 2023 at 12:39:37 UTC, thebluepandabear wrote:
...
The `foreach` worked for that case since `bark` is a method of
`IDog`. `update` is not so a conversion to `Button[]` is needed.
In that case, you could do a casting like this:
import std.stdio, std.conv;
interface IDog {
void bark();
}
class Dog: IDog{
string s;
this(string _s){s = _s;}
void bark(){writeln(s);}
void update(string _s){ s ~= " - " ~ _s; }
}
class List{
IDog[] dogs;
void add(T)(T d){ dogs ~= d; }
}
void main(){
auto d1 = new Dog("meaw!");
auto d2 = new Dog("wof!");
auto l = new List();
l.add(d1);
l.add(d2);
foreach(i,d; l.dogs){ // I'm using 'i' just to show each
update.
(cast(Dog)d).update(to!string(i));
d.bark();
}
}
Prints:
meaw! - 0
wof! - 1
Matheus.
Re: Why does this code only work with `std.conv.to` whilst not with `cast`?
On Sunday, 8 January 2023 at 11:29:10 UTC, thebluepandabear wrote:
...
There is an explanation here:
https://forum.dlang.org/post/tqukutfzeaxedunuv...@forum.dlang.org
But in any case I'd like to point it out that I think you could
do that foreach without casting or std.conv by just omitting the
type of the variable you're iterating:
import std.stdio, std.conv;
interface IDog {
void bark();
}
class Dog: IDog{
string s;
this(string _s){s = _s;}
void bark(){writeln(s);}
}
class List{
IDog[] dogs;
void add(T)(T d){ dogs ~= d; }
}
void main(){
auto d1 = new Dog("meaw!");
auto d2 = new Dog("wof!");
auto l = new List();
l.add(d1);
l.add(d2);
foreach(d; l.dogs){ // No type informed for "d"
d.bark();
}
}
Prints:
meaw!
wof!
Matheus.
Re: Address of a class object
On Sunday, 1 January 2023 at 09:01:24 UTC, Paul wrote:
...
If the size of MyClass is 9 bytes why do MyClassO1 & O2
addresses only differ by 4 bytes?
Because those addresses(4FFB20 4FFB24) are the addresses of
the class **variables**, not the addresses of the **objects**
themselves?
Because MyClass01 and MyClass02 are pointers and in your case
they differ 4 bytes each other.
Now you could do this:
import std.stdio, std.traits;
class MyClass {char[16] c;}
void main() {
writeln(" Size Alignment Type\n",
"=");
size_t size = __traits(classInstanceSize, MyClass);
size_t alignment = classInstanceAlignment!MyClass;
writefln("%4s%8s %s",size, alignment, MyClass.stringof);
// my test code added
MyClass MyClassO1;
MyClass MyClassO2;
writeln("\n",,"\t",);
writeln("\n",&(MyClassO1.c),"\t",&(MyClassO2.c));
MyClassO1 = new MyClass();
MyClassO2 = new MyClass();
writeln("\n",,"\t",);
writeln("\n",&(MyClassO1.c),"\t",&(MyClassO2.c));
}
In this machine it will print:
Size Alignment Type
=
32 8 MyClass
7FFD890C64107FFD890C6418 <-
10 10 <- Note here [&(MyClassO1.c),
&(MyClassO2.c)]
7FFD890C64107FFD890C6418 <- (Same address)
7FD0435D8010 7FD0435D8030 <- Now after instantiation!
[&(MyClassO1.c), &(MyClassO2.c)]
Finally as you can see I changed your:
class MyClass {char c;}
to:
class MyClass {char[16] c;}
Because from char[1] to char[16] it will keep the address
difference for [&(MyClassO1.c), &(MyClassO2.c)] by 0x20 (32):
7FD0435D80107FD0435D8030
If I change to char[17]
The difference goes up from 0x20 (32) to 0x30 (48), and keeps
that way until char[32]:
7FD0435D80107FD0435D8040
char[33] will increase again by 16 bytes and so on.
Matheus.
Re: dChar Error
On Friday, 30 December 2022 at 22:02:41 UTC, Ali Çehreli wrote: On 12/30/22 13:54, matheus wrote: > But yes I think it will generate a copy (mutable) based on this test: In this case it does copy but in the case of dchar[] to dchar[], there will be no copy. Similarly, there is no copy from immutable to immutable. Very interesting I did some testing and you are right. So better to stick with .dup! Thanks for the info, Matheus.
Re: dChar Error
On Friday, 30 December 2022 at 15:28:05 UTC, Salih Dincer wrote:
... In this case, std.conv.to can be used for mutable dchars,
right? For example, is this solution the right approach?
```d
auto toDchar(S)(inout S str) {
import std.conv : to;
return str.to!(dchar[]);
}
void main() {
auto str3 = "ÜÇ ON "d;
auto str4 = "BİR İKİ BEŞ "d.dup;
auto str5 = "DÖRT ALTI YEDİ ".toDchar;
//str5.fun(5);
}
```
Unfortunately I can't say because I'm not a skilled D programmer,
I use mostly as a C on steroids.
But yes I think it will generate a copy (mutable) based on this
test:
void main(){
import std.stdio;
import std.conv;
auto str1 = "BİR İKİ BEŞ ";
auto str2 = str1;
auto str3 = str2.to!(dchar[]);
writeln(str1, ", ", str1.ptr);
writeln(str2, ", ", str2.ptr);
writeln(str3, ", ", str3.ptr);
str3[0] = 'A';
writeln(str3, ", ", str3.ptr);
}
It prints:
BİR İKİ BEŞ , 5641226D8200
BİR İKİ BEŞ , 5641226D8200
BİR İKİ BEŞ , 7FB466EAE000
AİR İKİ BEŞ , 7FB466EAE000
So for str2 = str1 it is just a case of passing the reference,
and both are pointing to the same address, while in the case of:
"str3 = str2.to!(dchar[]);", the address is different, and
accepts changing its content (str3[0] = 'A').
In the docs: https://dlang.org/phobos/std_conv.html#to
"String to string conversion works for any two string types
having (char, wchar, dchar) character widths and any combination
of qualifiers (mutable, const, or immutable)."
But I couldn't find if the target will be mutable, but I think it
will be, unless explicitly otherwise with a cast I believe.
Anyway I would wait and see if someone more skilled could shed a
light.
Matheus.
Re: dChar Error
On Friday, 30 December 2022 at 10:03:20 UTC, Salih Dincer wrote:
On Friday, 30 December 2022 at 09:29:16 UTC, novice2 wrote:
On Friday, 30 December 2022 at 04:43:48 UTC, Salih Dincer
wrote:
...
// example one:
char[] str1 = "cur:€_".dup;
...
// example two:
dchar[] str2 = cast(dchar[])"cur:€_"d;
...
SDB@79
why you use .dup it example one, but not use in example two?
dchar[] str2 = cast(dchar[])"cur:€_"d.dup;
If I do not use .dup in the 1st example and convert as
cast(char[]), it gives an error. However, in the 2nd example
using .dup does nothing. It's not working anyway!
...
Are you sure about that?
Because replacing this:
dchar[] str2 = cast(dchar[])"cur:€_"d;
with this:
dchar[] str2 = (cast(dchar[])"cur:€_").dup;
Worked for me:
8: [€_]
[cur:$ _]
6: [€_]
[cur$ _]
A small example of the problem:
import std.stdio;
void main(){
dchar[] str1 = (cast(dchar[])"cur:€_").dup;
dchar[] str2 = (cast(dchar[])"cur:€_");
str1[0] = '1';
//str2[0] = '1'; // this will give: Error: program killed by
signal 11
}
Matheus.
Re: How Can i see associative array implement , is where has pseudocode write in Dlang?
On Thursday, 29 December 2022 at 11:24:38 UTC, lil wrote: How Can i see associative array implement , is where has pseudocode write in Dlang? Maybe this will help: https://github.com/dlang/phobos/blob/master/std/array.d Matheus.
Re: Thinking about the difference between fixed and 'dynamic' arrays.
On Tuesday, 29 November 2022 at 23:25:46 UTC, DLearner wrote: On Tuesday, 29 November 2022 at 19:06:20 UTC, rikki cattermole wrote: [...] Please see the following example: ... I think this was discussed before a few weeks ago here (But I don't remember the thread), and this is a design choice, for example this: VarArr2 = VarArr1; VarArr2 is just pointing to the same address of VarArr1 as you can see by: writeln(VarArr1.ptr); writeln(VarArr2.ptr); To do what you want, you need to use "dup": VarArr2 = VarArr1.dup; Now it will work as you expect. I think this is confusing but in the end it's a design choice, instead of copy just point, and if you need to copy, you need to it explicitly. Matheus.
Re: Is defining get/set methods for every field overkill?
On Friday, 18 November 2022 at 09:42:21 UTC, []() {}() wrote:
...
I think you missed the point of that video very badly.
By the way just a few points from that video:
Around: 2:32 -> "Never ever put in an 'accessor' until it
actually does something...".
Around: 3:10 -> "If there is an 'accessor' it had better do
something in there...".
Matheus.
Re: Is defining get/set methods for every field overkill?
On Thursday, 17 November 2022 at 04:39:35 UTC, thebluepandabear wrote: ... It's not a lot of code that has been added but if you have a class with say 10 different fields, adding getter methods would definitely increase the code size by a lot, so what are you guys thoughts on this? Food for thought: https://yewtu.be/watch?v=_xLgr6Ng4qQ or https://www.youtube.com/embed/_xLgr6Ng4qQ Matheus.
Re: Why am I getting different array size depending where I calling?
On Monday, 14 November 2022 at 21:07:42 UTC, Adam D Ruppe wrote:
On Monday, 14 November 2022 at 21:00:38 UTC, matheus wrote:
void[] getFoo(){
writeln(cast(int[])bar);
auto foo = getFoo();
writeln(foo);
Prints:
[1, 0]
[2, 0, 0, 0, 0, 0, 0, 0]
Looking through godbolt.org the ASM generated with both
So why the array generated from getFoo() is 4 times bigger
than the other?
It isn't. You're casting one to int[] and not casting the
other, leaving it as void[], which writeln will interpret as
just raw bytes.
Since an int is 4x bigger than a byte, casting it to int shows
1/4 the number of ints.
But the actual array is the same.
Oh my, you're absolutely right... I can't believe I missed that.
Thanks Adam,
Matheus.
Why am I getting different array size depending where I calling?
Hi all,
Well my doubt is pretty much the title for the snippet below:
import std.stdio;
void[] getFoo(){
void[] _ = new void[int.sizeof*2];
(cast(int[])_)[0] = 2;
return _;
}
void main() {
void[] bar = new void[int.sizeof*2];
(cast(int[])bar)[0] = 1;
writeln(cast(int[])bar);
auto foo = getFoo();
writeln(foo);
return;
}
Prints:
[1, 0]
[2, 0, 0, 0, 0, 0, 0, 0]
Looking through godbolt.org the ASM generated with both
void[] bar = new void[int.sizeof*2];
or
void[] _ = new void[int.sizeof*2];
is the same:
mov rdi, qword ptr [rip + TypeInfo_Av.__init@GOTPCREL]
mov esi, 8
call_d_newarrayT@PLT
mov qword ptr [rbp - 16], 8
mov qword ptr [rbp - 8], rdx
So why the array generated from getFoo() is 4 times bigger than
the other?
Thanks in advance,
Matheus.
Re: Comparison of two 'dynamic arrays'.
On Sunday, 13 November 2022 at 17:10:23 UTC, DLearner wrote:
...
The slight generalisation shown at bottom also worked.
However, is there a way of avoiding the for-loop?
...
I don't have too much knowledge in D, but I think so. (My main
language is C).
Well, one way to make things "better" would be creating a
constructor inside that struct with opCall, something like this:
import std.stdio;
void main() {
struct test_struct {
char[] Txt;
static test_struct[] opCall(test_struct[] e){
auto _ = e.dup;
foreach(i,v; e[0].Txt){
_[0].Txt = e[0].Txt.dup;
}
return _;
}
}
test_struct[] A;
A.length = 1;
A[0].Txt.length = 1;
A[0].Txt[0] = 'X';
writeln(A);
auto B = test_struct(A);
writeln(A, B);
A[0].Txt[0] = 'Y';
writeln(A, B);
}
There still a loop over there, so let's wait for some advanced
users to destroy this. :)
Matheus.
Re: Comparison of two 'dynamic arrays'.
On Sunday, 13 November 2022 at 15:45:40 UTC, DLearner wrote:
On Sunday, 13 November 2022 at 14:39:26 UTC, Siarhei Siamashka
wrote:
On Sunday, 13 November 2022 at 14:28:45 UTC, DLearner wrote:
Creating a step 1.5:
```
int[] B = A;
```
```D
auto B = A.dup;
```
This will create a copy of A rather than referencing to the
same buffer in memory.
Tested:
```
void main() {
import std.stdio;
struct test_struct {
char[] Txt;
}
test_struct[] A;
A.length = 1;
A[0].Txt.length = 1;
A[0].Txt[0] = 'X';
writeln(A);
auto B = A.dup;
writeln(A, B);
A[0].Txt[0] = 'Y';
writeln(A, B);
}
```
Got:
```
[test_struct("X")]
[test_struct("X")][test_struct("X")]
[test_struct("Y")][test_struct("Y")]
```
Expected last line to be Y,X not Y,Y.
You should add the code below after "auto B = A.dup;":
B[0].Txt = A[0].Txt.dup;
The "Txt" property inside B is still referencing A without the
above.
Matheus.
Re: What's the correct way of creating an instance of class in D?
On Thursday, 3 November 2022 at 04:41:14 UTC, Siarhei Siamashka wrote: ... https://dlang.org/spec/class.html Matheus.
Re: Is "auto t=T();" not the same as "T t;"?
On Tuesday, 25 October 2022 at 20:12:25 UTC, Paul Backus wrote: On Tuesday, 25 October 2022 at 17:54:16 UTC, Salih Dincer wrote: On Tuesday, 25 October 2022 at 17:18:35 UTC, Paul Backus wrote: It's not a bug. They're pointing to the exact same instance of `A` in memory: I don't understand? So I don't understand why it causes problems with dynamic arrays! So why is there nothing wrong with the static array in the example below? Static arrays are value types. When you copy a static array, the copy's data is stored in a separate block of memory from the original: ```d int[1] a = [1]; int[1] b = a; assert([0] !is [0]); // different memory ``` Dynamic arrays are reference types. When you copy a dynamic array, both copies point to the same block of memory: ```d int[] a = [1]; int[] b = a; assert([0] is [0]); // same memory ``` In order to create a copy of a static array with its own block of memory, separate from the original, you have to use the built-in `.dup` method: ```d int[] a = [1]; int[] b = a.dup; assert([0] !is [0]); // different memory ``` This is interesting, I understand the point of "reference vs copy", and I'm OK with this design choice of, but I wonder in the case of newcomers if this is a case the generate more problem understanding this rules, like we are having here. Matheus.
Re: Design question regarding saving changes in the original array and/or returning a new set
On Sunday, 23 October 2022 at 17:36:25 UTC, Paul Backus wrote: On Sunday, 23 October 2022 at 13:32:44 UTC, matheus wrote: ... You say your idea is "like passing some argument", so why not actually pass an argument? For example: ... Hi, thanks for the example, and yes I'd like to do that, but I'm looking for this "chaining" things which seems to be some sort of pattern these days. Like I said to Sergey, I think I'll use the library as example, except that I think that I'd do the otherwise, calling just "sort()" would give a duplicate, and chaining with "save()", "inplace()" or whatever name is would sort in place (Caller). Thanks, Matheus.
Re: Design question regarding saving changes in the original array and/or returning a new set
On Sunday, 23 October 2022 at 16:16:55 UTC, Sergey wrote: On Sunday, 23 October 2022 at 15:47:27 UTC, matheus wrote: Hi H. S. Teoh, I think you misunderstood my question, since English is not my first language maybe this was a problem from my part, but anyway, I'm not talking about "sort" from main library. This example was if I had designed my "own version". Matheus. Hi, Matheus. I'm not an expert in programming :) But I believe it should be up to you. How you make your function... Hi, yes I know but I'd like to know what is the most "common way" of doing this. I think I'll use the library as example, except that I think that I'd do otherwise, calling "sort()" would give a duplicate, and chaining with "save()" or "inplace()" would sort the caller. Thanks, Matheus.
Re: Design question regarding saving changes in the original array and/or returning a new set
Hi H. S. Teoh, I think you misunderstood my question, since English is not my first language maybe this was a problem from my part, but anyway, I'm not talking about "sort" from main library. This example was if I had designed my "own version". Matheus.
Design question regarding saving changes in the original array and/or returning a new set
Hi, I have a design question and I'd like to hear some advice. Let's say that I want to create a method to sort an array: arr.sort(asc); I think usually this would usually return a new set of that array but now sorted. But If I want to do this in the original, I think I would do this: arr.sort(asc).save(); The problem with this, it would create a new set and assign/copy back to the caller, which would be a waste. So I thought about this: arr.save.sort(asc); Then save would tell to "sort()" what to do beforehand, like passing some argument saying that the sort should be done direct in the caller and no copy. Is this (The latter) an approach you would use? Or there is a better way to do this. By the way in this design I'd like to have both options, return a new set and/or change the original. Thanks in advance, Matheus.
Re: How do I correctly install packages for use with Visual Studio?
On Sunday, 16 October 2022 at 11:09:31 UTC, Decabytes wrote: I'm trying to set up Visual Studio 2022 with Visual D, and I'm running into issues trying to get my project to build correctly. It's a double whammy because I've never used Visual Studio before (Just an Emacs Guy), but I need to debug my D programming and according to the [documentation](https://wiki.dlang.org/Debuggers) this is my only option on Windows. I don't know if anything changed significantly, but I used to debug on Windows with WinDbg without any IDE. Maybe this is useful: https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/debugger-download-tools Matheus.
Re: Doubt about char.min/max == typeid(char)
On Friday, 7 October 2022 at 01:02:57 UTC, torhu wrote: On Friday, 7 October 2022 at 00:13:59 UTC, matheus wrote: Hi, Could anyone please tell me why the properties of min/max of a char returns a "char type" and not a value as an int? Well, why whould the highest and lowest values of a type be of a different type..? Hmm well I was thinking the min/max as a range/limits, in this case 0 to 255 or it could be -128 to 127 if signed, or in a case of a bool: 0 to 1, but now I see it returns the min/max value of the type itself, like the latter false/true. I had my reasoning based on my experience with C. Thanks, Matheus.
Doubt about char.min/max == typeid(char)
Hi,
Could anyone please tell me why the properties of min/max of a
char returns a "char type" and not a value as an int?
I just got this while playing around:
void main(){
import std.stdio;
writeln(char.max); // "nothing"
writeln(typeid(char.max)); // "char"
writeln(cast(int)char.max); // 255
}
Thanks in advance,
Matheus.
Re: Why allow initializers of non-static members that allocate?
On Saturday, 11 June 2022 at 01:52:58 UTC, Mike Parker wrote:
...
That's because static arrays are allocated as part of the
instance:
...
Yes I understood the problem, but the naive me was thinking that
in this example:
struct S{
int[] arr = new int[](5);
}
For some reason this would be transformed as a statically "int[5]
arr" in the case of structs.
But now I see that's not the case and "arr" points to whatever
was allocated by "new", and will share across the instances of S
(Since it's the same address).
... So would you then really want a warning every time you
initialize a static array field?
Well would this be annoying? Yes, mainly if I already know this,
but if not, then it would be like a nice to know warning for
newbies like myself. By the way this would be only in the cases
that a static array field being initialized with dynamic
allocation like in the case of struct declaration, not on every
place.
...
So the question in each case would be, where's the line between
helpful and annoying?
Well I like to think about this like the "-Wall" flag in C
compilers, you need to go for it, and you just dismiss the
warning in such case if you don't agree or know what you're doing.
...
The compiler should be as helpful as it can, but it has to be
helpful without getting in the way. There's a significant
amount of learning by trial and error in any programming
language. So I think there has to be a distinction between
things like "easy to do by accident even when you know the
deal" and "once you learn it, you're unlikely to do it again".
Yes no doubt about it, by the way like I said, I never used this
form to initialize fields in structs, I always used the "T[n]
member", but in this particular case the result would have been
very different from what I expected.
Anyway I'm always lurking around this Forum and learning new
things.
Thanks,
Matheus.
PS: I'm ESL so sorry for my English mistakes.
Re: Why allow initializers of non-static members that allocate?
On Friday, 10 June 2022 at 07:49:43 UTC, Mike Parker wrote:
...
And it *is* documented:
Struct fields are by default initialized to whatever the
Initializer for the field is, and if none is supplied, to the
default initializer for the field's type.
The default initializers are evaluated at compile time.
https://dlang.org/spec/struct.html#default_struct_init
Hmm I understand the text but for this intializers I was
expecting new address with length 5, for example:
import std.stdio;
struct S{
int[] arr = new int[](5);
int[2] arr2;
}
void main(){
S s1, s2;
s2.arr[0] = 42;
writeln(s1.arr[0], " address: ", [0]);
writeln(s2.arr[0], " address: ", [0]);
s2.arr2[0] = 10;
writeln(s1.arr2[0], " address: ", [0]);
writeln(s2.arr2[0], " address: ", [0]);
}
Prints:
42 address: 5586F5BD9CC0
42 address: 5586F5BD9CC0
0 address: 7FFFC65C7A20
10 address: 7FFFC65C7A40
And as it can be seen: s1.arr and s2.arr shares the same address.
So, in the case of "int[] arr = new int[](5)", an array of length
5 of type int will be instantiated and its address will be shared
among whoever instantiates "S" and be pointed and accessed
through arr.
In the second case, "int[2] arr2", 2 consecutive integer spaces
in memory will be allocate independently for each "instantiation"
of "S", so different address.
I never saw this before (I mean I never wrote the first case),
I'm used to the "int[2] arr2;" way of declaring it, but if I had
looked this code without knowing this, I'd be certain that s1.arr
and s2.arr would have different addresses.
This is a bit weird (At least for a newbie like me), I really
think the compiler should emit an warning about this.
Matheus.
Re: Comparing Exceptions and Errors
On Sunday, 5 June 2022 at 15:07:13 UTC, kdevel wrote: ... I would refactor the code: I really liked this one. The way it solves and at same time restrict the "external access" with that struct of (a,b) makes the code easier to maintain too. Glad I keep lurking around this forum. Matheus.
Re: Compiler switch for integer comparison/promotion to catch a simple error
On Monday, 30 May 2022 at 13:15:12 UTC, bauss wrote: Good luck convincing Walter that this is a mistake :) I don't think this is a matter of convincing or changing the behavior, I think that a flag for this case (If not exist) should be added as a warning. A language where some people use to spread the phrase "D as better C" should at least have this as flag/warning too. Matheus.
Re: Compiler switch for integer comparison/promotion to catch a simple error
On Sunday, 29 May 2022 at 01:35:23 UTC, frame wrote: Is there a compiler switch to catch this kind of error? ```d ulong v = 1; writeln(v > -1); ``` IMHO the compiler should bail a warning if it sees a logic comparison between signed and unsigned / different integer sizes. There is 50% chance that a implicit conversion was not intended. Well I don't know about this, but of course I think (That if not) we should have at least a flag like we have with GCC (-Wextra). Searching about I found in this topic: https://forum.dlang.org/post/hhpacodmcibejatqz...@forum.dlang.org "Good luck adding a warning into DMD. After years there still isn't a warning for unsigned/signed comparisons." This is from 2017, so let's wait for experienced weighting in. Matheus.
Re: Installing DMD on linux via snap
On Wednesday, 18 May 2022 at 15:27:57 UTC, rikki cattermole wrote: Snap package source: https://github.com/dlang-snaps/dmd.snap/ Hasn't been updated in 3 years. I see... and even that I found my answer elsewhere, this problem was already discussed there: https://github.com/dlang-snaps/dmd.snap/issues (GCC isn't part of the dependencies). But there was no further progress. Matheus.
Installing DMD on linux via snap
Hi, Even my problem is already solved, I'm passing this information because I don't know if you are aware. Yesterday I needed to install DMD on a fresh installed version of Linux, so since I was using Xubuntu I decided to use snap. sudo snap install dmd Then a warning appeared saying that because some permissions I should add --classic, OK I added and the installation proceeded. So I just ran DMD alone and I got the version and some info, but when I tried to compile a simple Hello world to check if everything was really fine, I was greeted with this: cc: No such file or directory --- errorlevel 255 Looking online I found my answer, this was probably because it was missing GCC, then I did: apt-get install build-essential And after that it worked, but I wonder... couldn't we get a hint about this after or even before installing DMD? I remember installing other applications and being asked to install additional libraries/packages. Couldn't we have the same? Matheus.
Re: Question on shapes
On Tuesday, 17 May 2022 at 04:37:58 UTC, Ali Çehreli wrote:
...
2) If you want to have a shape hierarchy, then you can start by
defining its interface and implement that interface by concrete
shape types. Drawing is ordinarily handled by member functions:
...
Hi Ali, I'm not the author but I have a question, in your second
example, let's say that sometimes it would be required to "draw"
with some scale factor, so (As a newbie) I would do something
like this:
interface Shape {
void draw();
void draw(float scale);
}
Then in Circle class:
void draw(float scale) {
writeln("This circle's radius is ", radius*scale);
}
void draw(){ draw(1); }
Then in Rectangular class:
void draw(float scale) {
writefln!"This rectangle's dimensions are
%sx%s."(width*scale,height*scale);
}
void draw(){ draw(1); }
So calling shape.draw() would draw with the original scale,
otherwise you could call as shape.draw(some_scale);
The problem is these are just 2 shapes and it could be much more,
so it would required to repeat all this.
In D there would be a better way to do such thing?
Thanks,
Matheus.
Re: What are (were) the most difficult parts of D?
On Wednesday, 11 May 2022 at 05:41:35 UTC, Ali Çehreli wrote: What are you stuck at? What was the most difficult features to understand? etc. To make it more meaningful, what is your experience with other languages? Ali I don't know if this will be helpful but here it goes, my user case is different since I use D as C on steroids. My first language was C and I have projects in this language which I still maintain and my brain is used to it, but depending the project I'll use D instead of C to use features like: GC, AA, Strings, Modules and maybe Classes if I feel like it, but I don't go to far from these and one reason is sometimes in a rich language with lots of features like D It gets hard to stay up to date. Now I know they must be useful to many others, but one thing that I don't like are the Attributes part, for me there are so many and this is a bit overwhelming (Again to me), for example need to think about: "@safe, @trusted, @system" while still prototyping may be a cumbersome, and if it's giving me trouble I'll just get rid of it. :) Again I should sit and read the documentation or your book again but it's hard to keep up-to-date sometimes with work and so on. By the way I used to program in C# at work too, but I stopped on whatever was the version that runs with .Net 4.6, again this is another case of language changing or adding so many features that I decided not to go on with it, since it's not required where I work (Occasionally I write a few batch programs here and there), and I'm current doing more database business at the company these days, Sorry for any English mistakes, Matheus.
Re: Library for image editing and text insertion
On Wednesday, 27 April 2022 at 00:03:25 UTC, Adam Ruppe wrote: ... I know about Adam Ruppe's work, I already used his terminal.d, but I think that unfortunately most people don't and I think it should be announced more in these parts. For me arsd is for D what stb is for C. I think in the first time running any D compiler, it should blink in the terminal in Yellow/Pink or whatever color you like, and show some info like: Are you starting a new project any need some libs? Do you know about arsd? If not then go to: https://github.com/adamdruppe/arsd. :) matheus.
Re: How to remove all characters from a string, except the integers?
On Friday, 4 March 2022 at 21:20:20 UTC, Stanislav Blinov wrote: On Friday, 4 March 2022 at 19:51:44 UTC, matheus wrote: OK but there is another problem, I tested your version and mine and there is a HUGE difference in speed: string s, str = "4A0B1de!2C9~6"; Unless I did something wrong (If anything please tell). By the way on DMD was worse, it was like 5x slower in your version. To add to the already-mentioned difference in allocation strategies, try replacing the input with e.g. a command-line argument. Looping over a literal may be skewing the results. Interesting and I'll try that way. Thanks. Matheus.
Re: How to remove all characters from a string, except the integers?
On Friday, 4 March 2022 at 20:38:11 UTC, ag0aep6g wrote: ... The second version involves auto-decoding, which isn't actually needed. You can work around it with `str.byCodeUnit.filter!...`. On my machine, times become the same then. Typical output: str: 401296 Tim(ms): 138 Tim(us): 138505 str: 401296 Tim(ms): 137 Tim(us): 137376 That's awesome my timing are pretty much like yours. In fact now with "byCodeUnit" it's faster. :) Thanks, Matheus.
Re: How to remove all characters from a string, except the integers?
On Friday, 4 March 2022 at 20:33:08 UTC, H. S. Teoh wrote: On Fri, Mar 04, 2022 at 07:51:44PM +, matheus via ... I don't pay any attention to DMD when I'm doing anything remotely performance-related. Its optimizer is known to be suboptimal. :-P Yes, in fact I usually do my coding/compiling with DMD because is faster, then I go for LDC for production and speed. Matheus.
Re: How to remove all characters from a string, except the integers?
On Thursday, 3 March 2022 at 23:46:49 UTC, H. S. Teoh wrote:
...
This version doesn't even allocate extra storage for the
filtered digits, since no storage is actually needed (each
digit is spooled directly to the output).
OK but there is another problem, I tested your version and mine
and there is a HUGE difference in speed:
LDC 1.27.1, with -O2:
import std.datetime.stopwatch;
import std.stdio: write, writeln, writef, writefln;
import std;
void printStrTim(string s,StopWatch sw){
writeln("\nstr: ", s
,"\nTim(ms): ", sw.peek.total!"msecs"
,"\nTim(us): ", sw.peek.total!"usecs"
);
}
void main(){
auto sw = StopWatch(AutoStart.no);
string s, str = "4A0B1de!2C9~6";
int j;
sw.start();
for(j=0;j<1_000_000;++j){
s="";
foreach(i;str){
(i >= '0' && i <= '9') ? s~=i : null;
}
}
sw.stop();
printStrTim(s,sw);
s = "";
sw.reset();
sw.start();
for(j=0;j<1_000_000;++j){
s="";
s = str.filter!(ch => ch.isDigit).to!string;
}
sw.stop();
printStrTim(s,sw);
}
Prints:
str: 401296
Tim(ms): 306
Tim(us): 306653
str: 401296
Tim(ms): 1112
Tim(us): 1112648
---
Unless I did something wrong (If anything please tell). By the
way on DMD was worse, it was like 5x slower in your version.
Matheus.
Re: How to remove all characters from a string, except the integers?
On Thursday, 3 March 2022 at 21:03:40 UTC, H. S. Teoh wrote:
...
--
void main() {
string s = "blahblah123blehbleh456bluhbluh";
auto result = s.filter!(ch => ch.isDigit).to!int;
assert(result == 123456);
}
--
Problem solved. Why write 6 lines when 3 will do?
Just because I'm a simple man. :)
I usually program mostly in C and when in D, I go in the same way
but using features like: GC, strings, AA etc.
Of course your version is a D'ish way of handling things, and I
can't contest it looks better visually. But if size was problem I
could have written:
void main(){
string s, str = "4A0B1de!2C9~6";
foreach(i;str){
(i >= '0' && i <= '9') ? s~=i : null;
}
writeln(s);
}
Well still 1 line off, but I goes with my flow. I mean this
example is a simple one, but usually I can see and understand
what a code in C is doing (more) easily than D just looking at
it. Don't even ask about C++, because I gave up. :)
Matheus.
PS: I spotted something on your code, you're converting the
result to int, this can lead to a overflow depending the values
in the string.
Re: How to remove all characters from a string, except the integers?
On Thursday, 3 March 2022 at 12:14:13 UTC, BoQsc wrote:
I've looked around and it seems using regex is the only closest
solution.
I'm a simple man who uses D with the old C mentality:
import std.stdio;
void main(){
string s, str = "4A0B1de!2C9~6";
foreach(i;str){
if(i < '0' || i > '9'){ continue; }
s ~= i;
}
writeln("Result: ", s);
}
Result: 401296
Matheus.
Re: https://run.dlang.io/ vs All dmd compilers (2.060 - latest)
On Monday, 28 February 2022 at 19:00:58 UTC, Matheus wrote: On Monday, 28 February 2022 at 17:49:36 UTC, Mike Parker wrote: ... Please try again. Testing. Matheus. It worked thanks! Matheus.
Re: https://run.dlang.io/ vs All dmd compilers (2.060 - latest)
On Monday, 28 February 2022 at 17:49:36 UTC, Mike Parker wrote: ... Please try again. Testing. Matheus.
Re: https://run.dlang.io/ vs All dmd compilers (2.060 - latest)
On Monday, 28 February 2022 at 02:31:57 UTC, Mike Parker wrote: ... Hey Parker, I think my IP still under surveillance, everytime I post I get: "Your message has been saved, and will be posted after being approved by a moderator." With VPN I can post without problem. Could you please take a look? Matheus.
Re: https://run.dlang.io/ vs All dmd compilers (2.060 - latest)
On Monday, 28 February 2022 at 08:11:15 UTC, Basile B. wrote: This was [reported before]. Apparently this would be caused by a timeout. [reported before]: https://forum.dlang.org/post/skc2dd$1o52$1...@digitalmars.com Apparently yes, but I think the return error should be clear to avoid guessing. I've been trying this for 2 weeks, I think there is something wrong there. Matheus.
https://run.dlang.io/ vs All dmd compilers (2.060 - latest)
Hi,
In "https://run.dlang.io; is the "All dmd compilers (2.060 -
latest)" not working anymore?
Because I always get: "Server error:"
I've been trying for like 2 weeks and I always get this "Server
Error: " message.
I even tried with this basic example:
void main(){
import std.algorithm, std.stdio;
"Starting program".writeln;
enum a = [ 3, 1, 2, 4, 0 ];
static immutable b = sort(a);
pragma(msg, "Finished compilation: ", b);
}
After one minute I think I get:
rdmd playground.d
Server error:
Thanks,
Matheus.
Re: how to handle very large array?
On Monday, 14 February 2022 at 13:20:45 UTC, MichaelBi wrote: thanks, you are all correct. i just change the algorithm and use the AA, previously using the naïve method...:), now solved perfectly. thanks again. You could have used a normal Int Array for this task too, you're dealing with numbers and could go with array of 9 elements 0..8, then move data circularly and adding new lives as hit -1. I pretty sure there is a Mathematical way to solve this, I mean without any Arrays, but I didn't bother about it since that even my basic JavaScript implementation runs in less than 1ms for 256 days in an old computer. Matheus.
Re: Wouldn't the compiler be smart with this shadowing variable?
On Saturday, 11 December 2021 at 01:02:36 UTC, frame wrote:
...
You probably want this:
```d
int j;
for({int i=0; j=0;} i<10; ++i){}
```
Beware, this syntax comes directly from hell
Well this works! :)
I'm just a bit intrigued by your last sentence. Is there anything
evil this may result or anything that I should be aware of?
Matheus.
Re: Wouldn't the compiler be smart with this shadowing variable?
On Friday, 10 December 2021 at 21:55:17 UTC, Siarhei Siamashka wrote: ... 2. reuse the existing "j" variable. Yes. But only one of them is a correct description of what actually happens when the compiler processes this code. So it's a good thing that the compiler is smart enough to reject ambiguous code and prevent humans from making mistakes. Hmm I see your point. And I just thought in cases like this the reuse should be the way, but I can see that this is a small snippet and in a big code this may hurt someone. Matheus.
Wouldn't the compiler be smart with this shadowing variable?
Hi,
Wouldn't the compiler be smart with this shadowing variable,
example:
void main(){
int j;
for(int i=0,j=0;i<10;++i){}
return;
}
onlineapp.d(3): Error: variable `j` is shadowing variable
`onlineapp.main.j`
So in the "for loop" shouldn't "i" be declared and "j" just be
assigned to 0?
I mean this is a bit weird, imagine I have different "for loops"
and in this situation I'll need to do this:
j=0;
for(int i=0;i<10;++i){}
Otherwise:
for(i=0,j=0;i<10;++i){}
This works, but now "i" variable will be out of the "for loop"
scope.
Matheus.
Re: How to loop through characters of a string in D language?
On Wednesday, 8 December 2021 at 11:23:45 UTC, BoQsc wrote:
...
The character I want to skip: `;`
My C way of thinking while using D:
import std;
string stripsemicolons(string input){
char[] s = input.dup;
int j=0;
for(int i=0;i
Re: Without multiples inheritance, how is this done?
On Saturday, 8 May 2021 at 18:33:35 UTC, Jack wrote:
...
but the class ExtendFoo and ExtendedBaa must inherit from Foo
and Baa, respectively. But how can I make it inherit the
routines from DRY class too without multiples inheritance? in
C++ I'd just do:
class ExtendedFoo : DRY, Base { /* ... */ }
class ExtendBaa : DRY, Base { /* ... */ }
What about this model:
class baseFoo{
// Implement foo stuff
}
class baseFooBar : baseFoo{
// Implement bar stuff
}
class FooBar : baseFooBar{
// Do your FooBar thing!
}
Matheus.
Re: Need for speed
On Thursday, 1 April 2021 at 19:00:08 UTC, Berni44 wrote: Try using ldc2 instead of dmd: ``` ldc2 -O3 -release -boundscheck=off -flto=full -defaultlib=phobos2-ldc-lto,druntime-ldc-lto speed.d ``` should produce much better results. Since this is a "Learn" part of the Foruam, be careful with "-boundscheck=off". I mean for this little snippet is OK, but for a other projects this my be wrong, and as it says here: https://dlang.org/dmd-windows.html#switch-boundscheck "This option should be used with caution and as a last resort to improve performance. Confirm turning off @safe bounds checks is worthwhile by benchmarking." Matheus.
Re: D's Continous Changing
On Thursday, 4 March 2021 at 05:44:53 UTC, harakim wrote: ... Yes it's a problem indeed. I had the same problem and that's worse when you don't upgrade very often. But let me tell something, where I work we have software in C#, do you think that upgrading was smoothly with all the tools that Microsoft provides? No it wasn't, and it gets worse with third party components. So this guy was hired just for that, port a very old code to the new framework, and after a month he did, yes it compiled alright... but the software didn't work as expected is some cases, some controls wasn't acting right and was very unreliable. Guess what? They are still developing with old framework until everything works correctly on the new framework. Matheus.
Development: Work vs Lazy Programmers... How do you keep sanity?
Hi, I didn't know where to post this and I hope this is a good place. I'm a lurker in this community and I read a lot of discussions on this forum and I think there a lot of smart people around here. So I'd like to know if any of you work with Lazy or even Dumb programmers, and If yes how do you keep your sanity? Matheus. PS: Really I'm almost losing mine.
Re: What is the difference between enum and shared immutable?
On Thursday, 29 October 2020 at 01:26:38 UTC, Mike Parker wrote: enum int[] arr = [1,2,3]; someFunc(arr); This is identical to someFunc([1,2,3]); Manifest constants have no address. They are effectively aliases for their values. Hi Mike, I really didn't know about this. Thanks for the information, Matheus.
Re: What is the difference between enum and shared immutable?
On Wednesday, 28 October 2020 at 22:07:06 UTC, H. S. Teoh wrote: ... (This is why it's a bad idea to use enum with an array literal, because every time it's referenced you get a new copy of the array.) ... Could you please give an example (Snippet) about this? Matheus.
Re: Is there something I'm not getting here?
On Tuesday, 27 October 2020 at 02:21:39 UTC, matheus wrote: On Tuesday, 27 October 2020 at 01:26:56 UTC, James Blachly wrote: On 10/26/20 9:19 PM, Ruby The Roobster wrote: Following code doesn't work(it's not the actual code but it represents it). Is there some rule about function overrides that I don't know about? ... The error I keep getting no matter what says: Error: Multiple Overrides of Same Function. Anybody know what I should do? It works for me. ... I think he is referring to this: ... I mean he may be having a duplicate method in the same class. Matheus.
Re: Is there something I'm not getting here?
On Tuesday, 27 October 2020 at 01:26:56 UTC, James Blachly wrote:
On 10/26/20 9:19 PM, Ruby The Roobster wrote:
Following code doesn't work(it's not the actual code but it
represents it). Is there some rule about function overrides
that I don't know about?
...
The error I keep getting no matter what says: Error: Multiple
Overrides of Same Function. Anybody know what I should do?
It works for me.
...
I think he is referring to this:
import std;
class B{
public override string toString(){
return null;
}
public override string toString(){
return toString(null);
}
}
void main() {
B b = new P();
}
Error: function `B.toString` multiple overrides of same function
You can view: https://www.jdoodle.com/iembed/v0/3rm
Matheus.
Re: Question about: ("1.1").to!int;
On Saturday, 24 October 2020 at 04:04:18 UTC, Виталий Фадеев
wrote:
On Friday, 23 October 2020 at 16:59:06 UTC, matheus wrote:
On Friday, 23 October 2020 at 13:57:41 UTC, Joseph Rushton
Wakeling wrote:
On Wednesday, 21 October 2020 at 22:50:27 UTC, matheus wrote:
Well since the caller is handling a string, shouldn't the
caller verify the content before any conversion?
What if:
"1.1.1".to!int
?
The algorithm will become more complicated?
Will the speed decrease?
I don't get...
Anyway this should fail, look "1.1" is one thing, "1.1.1" is
another thing as "1.a" is another thing.
Like I said before I think the behavior should be the same in
these cases:
(1.1).to!int = 1.
("1.1").to!int = Current is an error and IMO should be 1.
Now for your question:
1.1.1.to!int = Error: found `0.1` when expecting `,`.
"1.1.1".to!int = Should be the same as above.
Matheus.
Re: Question about: ("1.1").to!int;
On Friday, 23 October 2020 at 13:57:41 UTC, Joseph Rushton
Wakeling wrote:
On Wednesday, 21 October 2020 at 22:50:27 UTC, matheus wrote:
Since (1.1).to!int = 1, shouldn't the string value
("1.1").to!int at least try to convert to float/double and
then to int?
The thing is, that's a great way for hard-to-identify bugs to
creep into code. In these cases:
auto a = (1).to!int; // this works
auto b = ("1").to!int; // this works
auto c = (1.1).to!int; // this works and c = 1
... then what the programmer wants is unambiguous. In the
first case it's just converting int => int. In the second,
it's converting from a string that unambiguously represents an
integer value, to an int. And in the third, it's converting
_at programmer request_ from a double to an int (which has a
well-defined behaviour).
However, if ("1.1").to!int were to work, this would be the `to`
function making a judgement call on how to handle something
ambiguous. And while that judgement call may be acceptable for
your current use-case, it won't be for others.
I got it everything you said, but like a said previously:
(1.1).to!int vs ("1.1").to!int
One is a decimal literal while the other is a string
representation of a decimal.
To be honest I think the function is already making a judgment
call when I do (1.1).to!int and returns 1, I really fail to see
the difference when is ("1.1").to!int.
I agree with user1234: "The third case is just like `cast(int)
1.1` it's not _at programmer request_ from my point of view, it's
just that the `to` template has not be more restrictive than the
D `cast` expression. `to` should do at least what a `cast` do and
do more when there's no rule for the two types that are involved."
In particular, if `to` just accepted any string numerical
representation for conversion to int, how could the caller
explicitly _exclude_ non-integer input, if that is their
use-case?
Well since the caller is handling a string, shouldn't the caller
verify the content before any conversion?
Because a string may contain a integer, decimal representation or
neither one.
Finally I don't want to make a fuss of it, I just thought it was
a bit weird but it can be solved easily.
Thanks,
Matheus.
Re: Question about: ("1.1").to!int;
On Friday, 23 October 2020 at 08:09:13 UTC, Виталий Фадеев wrote:
On Wednesday, 21 October 2020 at 22:50:27 UTC, matheus wrote:
Hi,
import std.stdio, std.conv;
void main(string[ ] args) {
auto a = (1).to!int; // this works
auto b = ("1").to!int; // this works
auto c = (1.1).to!int; // this works and c = 1
auto d = ("1.1").to!int; // Doesn't work
}
[...]
1.1 is not int.
"to" works fine.
As solution,... "1.1" should be splitted to lexems: "1", ".",
"1". Then analyze and then converted to int.
Of course 1.1 it's not an integer, but since (1.1).to!int works I
thought that ("1.1").to!int should work too.
Matheus.
Question about: ("1.1").to!int;
Hi,
import std.stdio, std.conv;
void main(string[ ] args) {
auto a = (1).to!int; // this works
auto b = ("1").to!int; // this works
auto c = (1.1).to!int; // this works and c = 1
auto d = ("1.1").to!int; // Doesn't work
}
The forth line gives me:
std.conv.ConvException@/usr/include/dlang/dmd/std/conv.d(1898):
Unexpected '.' when converting from type string to type int
??:? pure @safe int std.conv.toImpl!(int,
immutable(char)[]).toImpl(immutable(char)[]) [0x55de76d9b4d7]
??:? pure @safe int
std.conv.to!(int).to!(immutable(char)[]).to(immutable(char)[])
[0x55de76d99a17]
??:? _Dmain [0x55de76d9986e]
Question:
Since (1.1).to!int = 1, shouldn't the string value ("1.1").to!int
at least try to convert to float/double and then to int?
Because for what I see "to!int" converts from: int,real but in
case of string only when it is a integer representation?
Matheus.
Re: Skipping or Stepping Through an Array?
On Wednesday, 21 October 2020 at 12:06:00 UTC, drug wrote:
There are two other way:
...
// using foreach
foreach (i; 0..a.length)
write(a[i], ", ");
...
Yes you can use foreach, but in this case will not act the way
the OP wanted. In his for loop example the "i" is incremented by
2: "i+=2".
So to perform what OP want with foreach it should be:
foreach (i,j;a){
if(i%2==0){ write(j, ", ");}
}
By the way it's possible to set a "step" value for "foreach"?
Matheus.
Re: Compiler is calling `_memset64` in betterC
On Sunday, 18 October 2020 at 19:24:28 UTC, Ferhat Kurtulmuş wrote: I plan to start a project in reasonable size, I wonder if I should really use betterC... if I encounter a bug like this, will I be stuck at it? The bug report says, it is a dmd specific problem, and LDC, my favorite d compiler, works well (tried it). So the "first party" compiler has a bug while the "third party" one works. That's weird. I would expect the other way around. Matheus.
Re: Working with pointers/adresses
On Thursday, 9 July 2020 at 17:24:33 UTC, matheus wrote:
On Wednesday, 8 July 2020 at 20:33:39 UTC, Paul Backus wrote:
import std.stdio;
void main()
{
int i;
readf("%d\n", i); // read a number
ubyte* p = cast(ubyte*) i; // convert it to a pointer
writeln(*p); // write the data at that address to the
console
}
Note that this program will almost certainly crash if you try
to run it, since modern computers do not allow programs to
read and write arbitrary memory locations.
I wonder if the question was more like intended to display the
value using pointers, ie:
import std.stdio;
void main(){
int i;
readf("%d\n", i);
int *p =
writeln(*p);
}
Because accessing arbitrary memory location seems very weird.
Matheus.
Or maybe he wanted to do this:
import std.stdio;
void main(){
int i;
readf("%d\n", i);
ulong address = cast(ulong)
ubyte* p = cast(ubyte*)address;
writeln(*p);
}
Matheus.
Re: Working with pointers/adresses
On Wednesday, 8 July 2020 at 20:33:39 UTC, Paul Backus wrote:
import std.stdio;
void main()
{
int i;
readf("%d\n", i); // read a number
ubyte* p = cast(ubyte*) i; // convert it to a pointer
writeln(*p); // write the data at that address to the
console
}
Note that this program will almost certainly crash if you try
to run it, since modern computers do not allow programs to read
and write arbitrary memory locations.
I wonder if the question was more like intended to display the
value using pointers, ie:
import std.stdio;
void main(){
int i;
readf("%d\n", i);
int *p =
writeln(*p);
}
Because accessing arbitrary memory location seems very weird.
Matheus.
Re: Privatize a few members to allow messing with them #11353
On Tuesday, 30 June 2020 at 20:01:43 UTC, Stanislav Blinov wrote:
On Tuesday, 30 June 2020 at 19:58:05 UTC, matheus wrote:
+loc.linnum = loc.linnum + incrementLoc;
This works because it was declared:
void linnum(uint rhs) { _linnum = rhs; }
Right?
Almost. Given these definitions:
@safe @nogc pure @property
{
const uint linnum() { return _linnum; }
void linnum(uint rhs) { _linnum = rhs; }
}
This:
loc.linnum = loc.linnum + incrementLoc;
is rewritten as:
loc.linnum(loc.linnum() + incrementLoc);
Alright and thanks again.
Matheus.
Re: Privatize a few members to allow messing with them #11353
On Tuesday, 30 June 2020 at 19:55:56 UTC, matheus wrote:
On Tuesday, 30 June 2020 at 19:46:35 UTC, Stanislav Blinov
...
@safe @nogc pure @property
{
const uint linnum() { return _linnum; }
const uint charnum() { return _charnum; }
void linnum(uint rhs) { _linnum = rhs; }
void charnum(uint rhs) { _charnum = rhs; }
}
...with which the += won't work (at least this variant, as the
getter isn't returning ref).
Oh I see now and thanks for the information.
By the way:
+loc.linnum = loc.linnum + incrementLoc;
This works because it was declared:
void linnum(uint rhs) { _linnum = rhs; }
Right?
Matheus.
Re: Privatize a few members to allow messing with them #11353
On Tuesday, 30 June 2020 at 19:46:35 UTC, Stanislav Blinov wrote:
On Tuesday, 30 June 2020 at 19:42:57 UTC, matheus wrote:
in this case this was more a style thing than anything else
right? Or is there something I'm not able to see?
Before the change, linnum and charnum are public variables, one
can do a += on them. After the change, they become properties
accessing, as the PR says, private variables:
@safe @nogc pure @property
{
const uint linnum() { return _linnum; }
const uint charnum() { return _charnum; }
void linnum(uint rhs) { _linnum = rhs; }
void charnum(uint rhs) { _charnum = rhs; }
}
...with which the += won't work (at least this variant, as the
getter isn't returning ref).
Oh I see now and thanks for the information.
Matheus.
Privatize a few members to allow messing with them #11353
Hi, I was looking the PR in DMD and I found this one: https://github.com/dlang/dmd/pull/11353/ One of the changes was: -loc.linnum += incrementLoc; +loc.linnum = loc.linnum + incrementLoc; I usually do the former and I particularly hate the later, so my question is, in this case this was more a style thing than anything else right? Or is there something I'm not able to see? Thanks, Matheus.
Re: What would be the advantage of using D to port some games?
On Wednesday, 24 June 2020 at 19:46:55 UTC, IGotD- wrote: A previous game implementation in D would be interesting and if you do it you are welcome to write your about experiences here. It's hard to say what features you would take advantage in D as I haven't seen the code in C/C++. However, one thing is clear D would be an easy port because it is so close to C/C++. Every algorithm can be ported directly without any bigger change. If it would Rust you would probably have to rethink some of the data structures and it would be more difficult. Another thing that is clear is that productivity would be high. With today's fast machines and old games you don't have to worry about any GC pauses as there is plenty of time for that. You can basically use the slow "scripting language" features of D. I would expect that D is in the C# ball park in productivity for such task. Thanks for the information. Yes I am thinking about doing it but at the same time I wonder if it's worth (technically speaking) port those games. I'll analyze if there's any part that could take the advantage of some D features that lacks in C/C++. Matheus.
Re: What would be the advantage of using D to port some games?
On Wednesday, 24 June 2020 at 19:14:48 UTC, IGotD- wrote: On Wednesday, 24 June 2020 at 18:53:34 UTC, matheus wrote: What I'd like to know from the experts is: What would be the advantage of using D to port such games? Can you elaborate your question a little bit more. Why would you want to port existing game code to another language to begin with? To see how the game could fit/run in D, like people are porting some of those games to Rust/Go and so on. When you mention "advantage", advantage compared to what? To the original language the game was written. For example taking DOOM (Written in C), in D what would be the features that someone would use to port this game, like using CTFE to generate SIN/COS table would be reasonable? I'm just looking for a roughly idea of this matter. Matheus.
