Question

I want to pass a string to my dll funcfion, but the function cannot get the value.
first I get the string from cmd line using GetMyParam function. it’s right.then, i pass
the value to my dll using innotest function.

function innotest(PName:string):Integer;
external 'innotest@E:\client\branch\maintain\1.4\bin\sdostate-debug\update.dll stdcall setuponly';

function GetMyParam(PName:string):string;
var
  CmdLine : String;
  CmdLineLen : Integer;
  i : Integer;
begin
    Result := '';
    CmdLineLen:=ParamCount();
    for i:=0 to CmdLineLen do
    begin
    CmdLine:=ParamStr(i);
    if CmdLine = PName then
      begin
          CmdLine:=ParamStr(i+1);
          Result := CmdLine;
          Exit;
      end;
    end;
end;

procedure CurStepChanged(CurStep: TSetupStep); 
var 
res: String;

begin
if (CurStep = ssPostInstall) and (Pos('setup', WizardSelectedTasks(false)) > 0)then
begin
res := GetMyParam('-myParam');
MsgBox(res, mbInformation, mb_Ok);
innotest(res);
end;
end;

Msgbox has the res value.
here is my dll code: the string’s length is 1.

DWORD Update::innotest(string str)
{
    LPCWSTR s = StringHelper::ANSIToUnicode(str).c_str();
    MessageBox(0,s,0,0);
    return 0;
}

Answer 1

You’re using string type in your function parameter, what is a sequence of characters in memory, that InnoSetup cannot reach directly. You have to use pointer to string type to get it to work. So when you are using Unicode InnoSetup, change your library function parameter to have an Unicode string pointer type the following way. Then you can keep your InnoSetup script as it is:

DWORD Update::innotest(LPCWSTR str)
{
    MessageBox(0,s,0,0);
    return 0;
}