The in operator and normal arrays

[Derek Parnell]

On Thu, 26 Apr 2007 01:30:46 +0200, Myron Alexander wrote:

> Hello.
> 
> I'm curious as to the reason for why the in operator only works with 
> associative arrays. I am working on a program where having an in 
> operator for a normal array would be useful. eg:
> 
> if ("string" in ["string1", "string2", "string3", ...]) {
>     do something
> }
> 
> Is there some other way to do this in the language without resorting to 
> a function or class method call?
> 
No. The D programming language does not contain a reserved word or built-in
function to scan through an array other than Associative Arrays.

The simplest is just a function call ...

   if (container.contains(elem) == true) {
        // do something
   }

where contains is something along the lines of ...

  bool contains(T)(T[] container,T elem)
  {
     foreach(e; container)
        if (e == elem) return true;
     return false;
  }

Unless you know some details about the internal ordering of the array
elements, a simple linear scan is all that can really be done.

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Justice for David Hicks!"
26/04/2007 9:33:19 AM