Re: Ordered list of strings in registry

OK, I used your tip and it worked well.

Thanks!


Le 21/11/2024 à 16:06, [email protected] a écrit :
> On 2024-11-21 05:55, Jean Truc wrote:
>> Hi,
>>
>> I'm looking for the best way to read and save an ordered list of
>> strings from and to the registry.
>>
>> Something like:
>>
>> [MY_LIST]
>>
>> key1=data1
>>
>> key2=data2
>>
>> key3=data3
>>
>> ...
>>
>> and reading writing the key/data entries in the order they appear in
>> the registry file.
>>
>> I've tried using an FXStringDict dictionary but it's not ordered. It
>> seems that the keys are read in a random order.
>>
>> Any ideas?
>
> FXRegistry (FXSettings) is a two-level hash table, i.e. a hash-table of
> FXStringDict, or string hash-tables.  By definition, its not sorted.
>
> The order is a function of the distribution of the hash-keys of the
> strings.  We're using the "FNV1a" hash algorithm to compute the
> keys, but older FOX versions used a different algorithm.  For
> access speed the exact hash algorithm doesn't matter, but fewer
> collisions is preferable as it maximizes the chance of items with
> the same key representing the same strings.
>
> You can walk the hash tables, skipping over the empty slots, then
> place the keys in an array, and sort it.
>
>   // Array with room for N keys...
>   const FXchar** array=...
>
>   for(i=j=0; i<stringdict.no(); ++i){
>     if(stringdict.empty(i)) continue;
>     array[j++]=stringdict.key(i).text();
>   }
>
>   // Sort N keys
>   qsort(array,N,sizeof(const FXchar*),strcmp);
>
> Then, mutatis mutandum, you'll have a sorted array.
> of the keys. Note the key strings themselves are
> not copied, only the pointers are..
>
> Hope this helps,
>
>    -- JVZ
>
>
>



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