Find in assoc array then iterate

[Siarhei Siamashka]

On Friday, 21 October 2022 at 22:03:53 UTC, Kevin Bailey wrote:
> I'm trying to do this equivalent C++:
>
>     unordered_map<string, int> map;
>
>     for (auto i = map.find(something); i != map.end(); ++i)
>         ...do something with i...
>
> in D, but obviously with an associative array. It seems that 
> it's quite
> easy to iterate through the whole "map", but not start from the 
> middle.
> Am I missing something obvious (or not so obvious) ?

Are you looking for something like this?

```D
import std;

void main() {
   int[string] map;
   foreach (v ; 1 .. 9)
     map[v.to!string] = v;
   writeln(map); // prints ["8":8, "4":4, "7":7, "6":6, "1":1, 
"5":5, "2":2, "3":3]

   auto something = "6";

   auto pointer_to_something = (something in map);
   if (pointer_to_something) {
     writeln(*pointer_to_something); // prints 6
     foreach (k, ref v ; map) {
       if (&v == pointer_to_something)
         break;
       writeln(v); // prints 8 4 7
     }
   }
}
```

This code finds something and then iterates elements between the 
"middle" and "begin". You asked for iterating between the 
"middle" and "end", but I don't see a big difference because the 
elements order is not guaranteed anyway. And just like Steven, 
I'm curious about what kind of practical utility is this supposed 
to have?