From the reference guide, december 2008 version:

"Dynamic arrays are reference counted: assignment of one dynamic array-type variable to another will let both variables point to the same array. Contrary to ansistrings, an assignment to an element of one array will be reflected in the other: there is no copy-on-write."

This is fine, but what is strange is that calling setlength DOES perform copy-on-write!

var a, b : array of longint;
begin
  setlength (a,2);
  b := a;
  setlength (a,5);
  writeln (length(b));   // I get 2, not 5
end.

Why this inconsistency? Seems like the behaviors for assigning an element and for using setlength should be similar.

Cheers,
David

It's the way Delphi works. In fact, calling setlength is /the/ way to make a dynamic array unique (afaik, the only alternative is calling copy, but that's slower in case the array already was unique.

Jonas