Function to print a diamond shape

[Jay Norwood via Digitalmars-d-learn]

On Monday, 21 April 2014 at 08:26:49 UTC, monarch_dodra wrote:
> The two "key" points here, first, is to avoid using appender. 
> Second, instead of having two buffer: "    " and "******\n", 
> and two do two "slice copies", to only have 1 buffer "    
> *****", and to do 1 slice copy, and a single '\n' write. At 
> this point, I'm not sure how we could be going any faster, 
> short of using alloca...
>
> How does this hold up on your environment?

Yes your solution is the fastest yet.  Also, its times are 
similar for all three compilers.   The range of execution times 
varied for different solutions from over 108 seconds down to 64 
msec.

I see that RefAppender's data() returns the managed array.  Can 
write() handle that?  It seems that would be more efficient than 
duplicating the  character buffer ... or perhaps writing directly 
to an OutBuffer, and then sending that to write() would avoid the 
duplication?

jay at jay-ubuntu:~/ec_ddt/workspace/diamond/source$ gdc -O2 main.d
jay at jay-ubuntu:~/ec_ddt/workspace/diamond/source$ ./a.out 
1>/dev/null
brad: time: 31865[ms]
sergei: time: 28596[ms]
jay2: time: 258[ms]
diamondShape: time: 7512[ms]
printDiamond: time: 200[ms]
printDiamonde2a: time: 140[ms]
printDiamonde2b: time: 137[ms]
printDiamond3: time: 503[ms]
printDiamonde2monarch: time: 86[ms]
jay at jay-ubuntu:~/ec_ddt/workspace/diamond/source$ dmd -release 
main.d
jay at jay-ubuntu:~/ec_ddt/workspace/diamond/source$ ./main 
1>/dev/null
brad: time: 108111[ms]
sergei: time: 33949[ms]
jay2: time: 282[ms]
diamondShape: time: 24567[ms]
printDiamond: time: 230[ms]
printDiamonde2a: time: 132[ms]
printDiamonde2b: time: 106[ms]
printDiamond3: time: 222[ms]
printDiamonde2monarch: time: 66[ms]
jay at jay-ubuntu:~/ec_ddt/workspace/diamond/source$ ~/ldc/bin/ldc2 
-O2 main.d
jay at jay-ubuntu:~/ec_ddt/workspace/diamond/source$ ./main 
1>/dev/null
brad: time: 20996[ms]
sergei: time: 24841[ms]
jay2: time: 259[ms]
diamondShape: time: 6797[ms]
printDiamond: time: 194[ms]
printDiamonde2a: time: 91[ms]
printDiamonde2b: time: 87[ms]
printDiamond3: time: 145[ms]
printDiamonde2monarch: time: 64[ms]
jay at jay-ubuntu:~/ec_ddt/workspace/diamond/source$