Is a dynamic array of Char allowed when the parameter type is open array of Char?

Question

I was looking at Delphi: array of Char and TCharArray "Incompatible Types" and started experimenting. What I discovered is rather interesting.

proc         


        

Answer 1

I think the reason is that array of Char is compatible with PChar, as this code does compile:

procedure Clear(AArray: array of Char);
var
  I: Integer;
begin
  for I := Low(AArray) to High(AArray) do
    AArray[I] := #0;
end;

var
  MyArray: array of Char;
  P: PChar;
begin
  Clear(P^);
end.

That is probably for historic reasons.
Hopefully Barry Kelly or Danny Thorpe will kick in and provide some more feedback on this.

--jeroen