How to efficiently generate a list of random integers within a range?

[WayneSherman]

For reference, bugs have been reported:
https://bugs.freepascal.org/view.php?id=36696
and
https://github.com/avk959/LGenerics/issues/3

[Thaddy]

For your Sattolo implementation, you have an error that requires an extra loop iteration.  When i = 0 then j = 0, so you are swapping a[0] with a[0].  Therefore:
Line 12:    while i > 0 do
should be
Line 12:    while i > 1 do

That is not true. You will introduce a fixed member in that case, so it is no longer random over the population.
I also think you do not understand that Sattolo takes one less iteration compared to Fisher-Yates....
Unless I am proven wrong, I am not likely to adapt the code: It is an implementation of the standard algorithm.

[WayneSherman]

Think about the last iteration when when i = 1

Code: Pascal  [Select][+][-]

1. while i > 0 do                    //i = 1, 1>0 is true so lets enter the while loop
2. begin
3.     dec(i);                       //i = 0 after this line
4.     j :=randomrange(Low(a),i);    //j = randomrange(0,0) = 0
5.     t:=a[i];a[i]:=a[j];a[j]:=t;   //since both i=0 and j=0 they both reference the same element and swap doesn't do anything.  so we didn't have to make this iteration
6.     write(a[i]:4);
7. end;

[avk]

For reference, bugs have been reported:
https://bugs.freepascal.org/view.php?id=36696
and
https://github.com/avk959/LGenerics/issues/3

Fixed in LGenerics.