Equivilent of STL Set in D ? ...

clayasaurus clayasaurus at gmail.com
Thu Oct 19 12:45:29 PDT 2006

Sean Kelly wrote:
> clayasaurus wrote:
>> Hello, I am converting some C++ code which happens to use STL Set to 
>> D. I was thinking of ways to implement set in D, but since I never got 
>> much into STL set in C++ I want to make sure I am thinking right.
>> 1) Are D's associative arrays equivalent to STL Set? I've read that 
>> Set is pretty much just a sorted associative array, can this 
>> functionality be achieved in D (using struct as a key type) by 
>> overloading opCmp?
> No.  D's associative array is implemented as a hash table, which is 
> unordered by nature.  If you require the elements to be sorted you'll 
> either have to use a different container or copy the values to an array 
> and sort the array before doing whatever you want to do with the sorted 
> values.  The word count example does this, for example.

Suppose that I don't need sorting, would an associative array work just 
as well? I'm looking at the code again and it isn't very clear that 
sorting is a requirement, just that I need to have fast insert, lookup 
(and if not in container, add it), and deletion.

Then again, if all that was needed was a hashmap, then I wonder why the 
author didn't use STL map.

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