what's the differences between AParam: P[Type] and var AParam: [Type] in dll import.

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#55

From: nhsoft.xy
Date: Thu, 08 Dec 2005 14:45

29 lines
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what's the differences between AParam: P[Type] and var AParam: [Type]
in dll import.
eg.
//C declaration:
//WORD DC_Mif_AntiCollision (DWORD *_dwSnr, BYTE _bMode = 1);
function DC_Mif_AntiCollision(var _dwSnr: Dword):WORD;Stdcall;external
'FOX_DC.dll';
function DC_Mif_AntiCollision(_dwSnr:PDword):WORD;Stdcall;external
'FOX_DC.dll';


And which is better. (It's a mifare1 api to operate IC Card Reader)
eg.
var
  dword_1: PDWORD;
  dword_2: DWORD;
begin
  //function DC_Mif_AntiCollision(var _dwSnr:
Dword):WORD;Stdcall;external 'FOX_DC.dll';
  GetMem(dword_1, SizeOf(DWORD));
  DC_Mif_AntiCollision(dword_1);
  DC_Mif_AntiCollision(dword_2);

  //function DC_Mif_AntiCollision(_dwSnr:PDword):WORD;Stdcall;external
'FOX_DC.dll';
  DC_Mif_AntiCollision(@dword_2);
  //TODO: which one is better???
end;
which one is better, and why?

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Subject: what's the differences between AParam: P[Type] and var AParam: [Type] in dll import.
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