There were a few deficiencies in the pi.d sample, including the display error pointed out by Sampsa.

I took the opportunity to modify the sample to show off dynamic array size language feature of D.  I also noticed that there is a calculation error on the last digit, so I modified the source to calculate one more digit than it would display.  This seems to solve the most egregious and obvious errors.  (i.e. PI does not equal 3.12, it should be 3.14).

I added a little checking so that we don't try to compute a negative number of digits--and print out a nice message.  Also, instead of forcing someone to never compute more than 4000 digits, I had it able to compute any number of digits the user entered.  Although, it does print out a warning "Be prepared to wait a while..." if the number is larger than 4000.

While I can't vouch for the perfectness of the math (I did nothing to change it), it no longer outputs obviously wrong info when low precision is used.

Please include it in the next version release samples.