Test for element in array

[Kirk McDonald]

BCS wrote:
> Dave wrote:
> 
>> BCS wrote:
>>
>>> Paolo Invernizzi wrote:
>>>
>>>> Hi all,
>>>>
>>>> Someone can suggest me the best way for testing the presence of an 
>>>> element in an array?
>>>>
>>>> Coming from python, something like...
>>>>
>>>> if( x in array_of_x && y in array_of_y ){
>>>>    ...
>>>> }
>>>>
>>>> The workaround, apart from using a simple 'for' loop, is to use an 
>>>> associative array, and test for key...
>>>>
>>>> ---
>>>> Paolo
>>>
>>>
>>>
>>>
>>> import std.stdio;
>>>
>>> void main()
>>> {
>>>     int[] a = new int[10];
>>>     int j=1;
>>>
>>>     // populate a
>>>     foreach(int i, inout int k; a) k=i;
>>>
>>>     if({foreach(i;a) if(i==j) return true; return false;})
>>>         writef("true\n");
>>>     else
>>>         writef("false\n");
>>> }
>>
>>
>>
>> That's a very elegant solution and it should work, but according to my 
>> tests it doesn't (darn). It never returns false.
>>
>> Set j = 100 once and give it a try.
> 
> 
> Bizarre
> 
> --     if({foreach(i;a) if(i==j) return true; return false;})
> ++     if({foreach(i;a) if(i==j) return true; return false;}())
> 
> this fixes it.
> 
> WT...
> 
> Oh.
> 
> {return false;}.typeof == bool delegate()
> {return false;}().typeof == bool
> 
> 

Hmmm. "Lambda properties." Fun.

-- 
Kirk McDonald
Pyd: Wrapping Python with D
http://dsource.org/projects/pyd/wiki