Function to print a diamond shape

[monarch_dodra]

On Sunday, 23 March 2014 at 18:28:18 UTC, Jay Norwood wrote:
> On Sunday, 23 March 2014 at 17:30:20 UTC, bearophile wrote:
>
>>
>> The task didn't ask for a computationally efficient solution 
>> :-) So you are measuring something that was not optimized for. 
>> So there's lot of variance.
>>
>> Bye,
>> bearophile
>
> Yes, this is just for my own education.   My builds are using 
> the dmd compiler on windows, and some  posts indicate I should 
> expect better optimization currently with the ldc compiler... 
> so maybe I'll get on a linux box and retest with ldc.

So it's about speed now? Then I submit this:

//----
void printDiamond(size_t N)
{
     char[32] rawSpace = void;
     char[64] rawStars = void;
     char* pSpace = rawSpace.ptr;
     char* pStars = rawStars.ptr;
     if (N > 64)
     {
         pSpace = new char[](N/2).ptr;
         pStars = new char[](N).ptr;
     }
     pSpace[0 .. N/2] = ' ';
     pStars[0 ..   N] = '*';

     N/=2;
     foreach         (n ; 0 .. N + 1)
         writeln(pSpace[0 .. N - n], pStars[0 .. 2*n+1]);
     foreach_reverse (n ; 0 .. N)
         writeln(pSpace[0 .. N - n], pStars[0 .. 2*n+1]);
}
//----