Question

The function I am using contains three parameters where one of which requires a flag (fCreationDisposition):

function MpqOpenArchiveForUpdate(lpFileName: LPCSTR; fCreationDisposition, dwHashTableSize: DWord): THandle; stdcall; external 'lmpqapi.dll';

The documentation states that there are five usable flags. However, when I use any of the flags Delphi tells me that it is an “undeclared identifier”.

Is there anything extra that I must add in order to be able to access the flags without Delphi telling me that it is an “undeclared identifier”?

Note: Under the uses section I have called for the function:

function MpqOpenArchiveForUpdate(lpFileName: LPCSTR; fCreationDisposition, dwHashTableSize: DWord): THandle; stdcall; external 'lmpqapi.dll';

Answer 1

You have to define the flags in your code. In Delphi, you have to define everything from scratch, you cannot utilize any pre-made API header files that belong to the DLL, like you can in C/C++. So you have to track down the flag numeric values (since the documentation does not provide them) and declare them in your code, eg:

// these values are just a guess, you will have
// to download the API and look them up...
const
  MOAU_CREATE_NEW = $1;
  MOAU_CREATE_ALWAYS = $2;
  MOAU_OPEN_EXISTING = $4;
  MOAU_OPEN_ALWAYS = $8;
  MOAU_MAINTAIN_LISTFILE = $10;