Re: Bug in usage of associative array: dynamic array with string as a key
On 6/30/23 17:42, Cecil Ward wrote:
> https://dlang.org/spec/hash-map.html#testing_membership in the language
> docs, under associative arrays - 13.3 testing membership. Would anyone
> else care to try that example out as that might be quicker?
I tried it by
1) Putting all the code inside a 'void main()' function
2) Pasting the code from the top of that page
and it works:
void main() {
int[string] aa; // Associative array of ints that are
// indexed by string keys.
// The KeyType is string.
aa["hello"] = 3; // set value associated with key "hello" to 3
int value = aa["hello"]; // lookup value from a key
assert(value == 3);
int* p;
p = "hello" in aa;
if (p !is null)
{
*p = 4; // update value associated with key
assert(aa["hello"] == 4);
}
}
> the only substantive
> change being deleting the variable p
Do you mean this:
aa.remove("hello");
That works too.
D's associative arrays have a few quirks but they work just fine. They
are not buggy as it may be inferred from some of the posts here.
Ali
Re: Bug in usage of associative array: dynamic array with string as a key
On Friday, 30 June 2023 at 19:05:23 UTC, Cecil Ward wrote:
I have code roughly like the following:
dstring str = "name"d;
uint ordinal = (( str in Decls.ordinals ) !is null) ?
Decls.ordinals[ str ] : -1;
struct Decls
{
uint[ dstring] ordinals;
}
//and
Decls.ordinals[ str ] = ordinal_counter++;
The problem is that it always returns ordinal== -1 from the
expression. Can you sort me out? I took this from the example
given in the language reference under arrays, testing for
membership (or similar, I forget the subssection title).
From good old printfs it seems to be the case that the array is
being populated (elsewhere) with the expected correct values.
Taking out the if doesn’t seem to help either. I don’t have a
way of examining the contents of the dynamic array directly to
check that they are actually being stored as expected, other
than seeing that that line of code is indeed being executed
with the expected values of str going in. Note that I’m using
32-bit dstrings everywhere, not strings of bytes.
Fool that I am. I did those good old printfs a while back, and
now I recheck them I see that something has become broken and it
seems that the insertions are not happening now. So thankyou for
your kindness and I’ll post again if that doesn’t solve the
non-issue.
Re: Bug in usage of associative array: dynamic array with string as a key
On Friday, 30 June 2023 at 21:25:23 UTC, H. S. Teoh wrote: On Fri, Jun 30, 2023 at 07:05:23PM +, Cecil Ward via Digitalmars-d-learn wrote: [...] It would help if you could post the complete code that reproduces the problem. Or, if you do not wish to reveal your code, reduce it to a minimal case that still exhibits the same problem, so that we can see it for ourselves. The snippets you provided do not provide enough information to identify the problem. T I would indeed need to cut it down massively, as the original code is ~2k lines. Mind you, I will just end up with the example at https://dlang.org/spec/hash-map.html#testing_membership in the language docs, under associative arrays - 13.3 testing membership. Would anyone else care to try that example out as that might be quicker? That’s because as all I did was copy that basically, with the only substantive change being deleting the variable p, but I’m still testing whether or not I get a null pointer. I thought I had checked that the insertions were all as expected, so I’ll go and recheck that next.
Re: Bug in usage of associative array: dynamic array with string as a key
https://forum.dlang.org/thread/duetqujuoceancqtj...@forum.dlang.org Try HashMap see if it is still a problem. If no, then it's another example of the built in AA problem.
Re: Bug in usage of associative array: dynamic array with string as a key
On Fri, Jun 30, 2023 at 07:05:23PM +, Cecil Ward via Digitalmars-d-learn wrote: [...] It would help if you could post the complete code that reproduces the problem. Or, if you do not wish to reveal your code, reduce it to a minimal case that still exhibits the same problem, so that we can see it for ourselves. The snippets you provided do not provide enough information to identify the problem. T -- What's the difference between a 4D tube and an overweight Dutchman? One is a hollow spherinder, and the other is a spherical Hollander.
Re: Bug in usage of associative array: dynamic array with string as a key
On 6/30/23 13:16, Cecil Ward wrote: On Friday, 30 June 2023 at 19:58:39 UTC, FeepingCreature wrote: Note that you can do `uint ordinal = Decls.ordinals.get(str, -1);`. Is the second argument an ‘else’ then, my friend? Yes, .get and friends appear in this table: https://dlang.org/spec/hash-map.html#properties Ali
Re: Bug in usage of associative array: dynamic array with string as a key
On Friday, 30 June 2023 at 19:58:39 UTC, FeepingCreature wrote:
On Friday, 30 June 2023 at 19:05:23 UTC, Cecil Ward wrote:
I have code roughly like the following:
dstring str = "name"d;
uint ordinal = (( str in Decls.ordinals ) !is null) ?
Decls.ordinals[ str ] : -1;
struct Decls
{
uint[ dstring] ordinals;
}
//and
Decls.ordinals[ str ] = ordinal_counter++;
The problem is that it always returns ordinal== -1 from the
expression. Can you sort me out?
Impossible to tell without a complete repro, I'm afraid. The
expression, at least, looks correct at first glance.
Note that you can do `uint ordinal = Decls.ordinals.get(str,
-1);`.
Is the second argument an ‘else’ then, my friend?
Re: Bug in usage of associative array: dynamic array with string as a key
On Friday, 30 June 2023 at 20:12:08 UTC, Ali Çehreli wrote:
On 6/30/23 12:05, Cecil Ward wrote:
> I have code roughly like the following:
>
> dstring str = "name"d;
Aside: One almost never needs dstring.
> uint ordinal = (( str in Decls.ordinals ) !is null) ?
> Decls.ordinals[ str ] : -1;
>
> struct Decls
> {
> uint[ dstring] ordinals;
Do you mean 'ordinals' is 'static'? Otherwise, Decls.ordinals
does not compile.
> }
>
> //and
> Decls.ordinals[ str ] = ordinal_counter++;
Are you doing that *after* you initialize 'ordinal' as you show
here? :)
Ali
Hi Ali, ‘ordinal’ is a static initialised explicitly with zero.
Re: Bug in usage of associative array: dynamic array with string as a key
On 6/30/23 12:05, Cecil Ward wrote:
> I have code roughly like the following:
>
> dstring str = "name"d;
Aside: One almost never needs dstring.
> uint ordinal = (( str in Decls.ordinals ) !is null) ?
> Decls.ordinals[ str ] : -1;
>
> struct Decls
> {
> uint[ dstring] ordinals;
Do you mean 'ordinals' is 'static'? Otherwise, Decls.ordinals does not
compile.
> }
>
> //and
> Decls.ordinals[ str ] = ordinal_counter++;
Are you doing that *after* you initialize 'ordinal' as you show here? :)
Ali
Re: Bug in usage of associative array: dynamic array with string as a key
On Friday, 30 June 2023 at 19:05:23 UTC, Cecil Ward wrote:
I have code roughly like the following:
dstring str = "name"d;
uint ordinal = (( str in Decls.ordinals ) !is null) ?
Decls.ordinals[ str ] : -1;
struct Decls
{
uint[ dstring] ordinals;
}
//and
Decls.ordinals[ str ] = ordinal_counter++;
The problem is that it always returns ordinal== -1 from the
expression. Can you sort me out?
Impossible to tell without a complete repro, I'm afraid. The
expression, at least, looks correct at first glance.
Note that you can do `uint ordinal = Decls.ordinals.get(str,
-1);`.
Bug in usage of associative array: dynamic array with string as a key
I have code roughly like the following:
dstring str = "name"d;
uint ordinal = (( str in Decls.ordinals ) !is null) ?
Decls.ordinals[ str ] : -1;
struct Decls
{
uint[ dstring] ordinals;
}
//and
Decls.ordinals[ str ] = ordinal_counter++;
The problem is that it always returns ordinal== -1 from the
expression. Can you sort me out? I took this from the example
given in the language reference under arrays, testing for
membership (or similar, I forget the subssection title).
From good old printfs it seems to be the case that the array is
being populated (elsewhere) with the expected correct values.
Taking out the if doesn’t seem to help either. I don’t have a way
of examining the contents of the dynamic array directly to check
that they are actually being stored as expected, other than
seeing that that line of code is indeed being executed with the
expected values of str going in. Note that I’m using 32-bit
dstrings everywhere, not strings of bytes.
