BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Using a C++ Com Object with Delphi          BorlandTalk.com Forum Index -> Delphi (General) View previous topic :: View next topic   Author Message Jim Sawyer Guest Posted: Sun Jul 18, 2004 5:35 pm    Post subject: Using a C++ Com Object with Delphi Using Delphi 7. Have a C++ DLL (com object). A function SendMessage is defined in the C++ header file as STDMETHOD (SendMessage)(VARIANT * psa_Data, SND_STATUS *pVal); I know that I need to pass an "array of byte" to this function. Specifically I need to pass the array aPortInquiryResponse which is aPortInquiryResponse[ 0 ] := 83; aPortInquiryResponse[ 1 ] := 77; aPortInquiryResponse[ 2 ] := 32; aPortInquiryResponse[ 3 ] := 49; aPortInquiryResponse[ 4 ] := 32; aPortInquiryResponse[ 5 ] := 115; to SendMessage. When I try IDXVetLab.SendMessage( aPortInquiryResponse ) I get the error message [Error] IDXTest1.pas(249): Types of actual and formal var parameters must be identical I don't know C++. Can anyone tell me what I am doing wrong? Thank you. Jim Sawyer Back to top Jim Sawyer Guest Posted: Mon Jul 19, 2004 3:33 pm    Post subject: Re: Using a C++ Com Object with Delphi Leon - I'm trying the following (I'm just including the necessary parts of the code): type aByteArray = Array of byte; pByteArray = ^aByteArray; procedure TVetLabForm.VetLabPacketQueued(Sender: TObject); var pPortInquiryResponse: pByteArray; begin ...... pPortInquiryResponse^[ 0 ] := 83; pPortInquiryResponse^[ 1 ] := 77; pPortInquiryResponse^[ 2 ] := 32; pPortInquiryResponse^[ 3 ] := 49; pPortInquiryResponse^[ 4 ] := 32; pPortInquiryResponse^[ 5 ] := 115; VetLab.SendMessage( pPortInquiryResponse ); ....... end; I still get the error message [Error] IDXTest1.pas(249): Types of actual and formal var parameters must be identical Incidently, the second parameter of the C++ function is it's return value (which also must be a pointer), but I'm not worried about that yet. Any suggestions??? Thank you, Jim Sawyer "Leon Zandman" <NOSPAMusenet (AT) wirwar (DOT) com> wrote Quote: Hi Jim, is defined in the C++ header file as STDMETHOD (SendMessage)(VARIANT * psa_Data, SND_STATUS *pVal); I know that I need to pass an "array of byte" to this function. You can't pass an "array of bytes" to that SendMessage function, because it only accepts pointers. That's what the asterisk character (*) means. So the first parameter is a pointer to a VARIANT and the second parameter is a pointer to a SND_STATUS type. When I try IDXVetLab.SendMessage( aPortInquiryResponse ) Well, the first thing that's wrong is that you supplied one parameter where there should be two (see above). The second thing is that it should be a pointer to the data, not the actual data itself. So the following would come closer: IDXVetLab.SendMessage(@aPortInquiryResponse); Greetz, Leon Back to top Jim Sawyer Guest Posted: Tue Jul 20, 2004 8:16 pm    Post subject: Re: Using a C++ Com Object with Delphi Quote: What does the Delphi IDE say when you press CTRL-SHIFT-SPACE while inside the brackets. It should tell you the count and type of the parameters. CTRL+SHIFT+SPACE displays the following: var Data: OleVariant Quote: type vTest: VARIANT; pTest: ^VARIANT; Do you mean for these two declarations to by types? If so shouldn't they have "=" signs between them? Do I still have a variable declared such as var aByteArray: Array[0..5] of byte; with which to stuff the values aByteArray[ 0 ] := 83; aByteArray[ 1 ] := 77; aByteArray[ 2 ] := 32; aByteArray[ 3 ] := 49; aByteArray[ 4 ] := 32; aByteArray[ 5 ] := 115; Then where do the vTest and pTest types come in? How do I use them to provide the var Data: OleVariant argument to the function VetLab.SendMessage( ?????? ); Also, does this indicate if one or two parameters are needed? I'm still lost as Hogan's goat!!! Quote: You are still not using two parameters. Unless the function makes use of a default parameter, you must supply the second one... Incidently, the second parameter of the C++ function is it's return value (which also must be a pointer), but I'm not worried about that yet. Even if it is used as a return value, so still must specify it. Greetz, Leon Back to top Jim Sawyer Guest Posted: Tue Jul 20, 2004 10:15 pm    Post subject: Re: Using a C++ Com Object with Delphi That both compiled and executed! I'm sending a port inquiry response back to a com port. Com ports are always a mess. So far it's not honoring my response, but that may be because I'm not sending it what it needs to see. But, thanks to you again, I'm one major step closer, getting it to execute the function. Thanks, Jim Sawyer PS - I'm only using one parameter... Also, I had to sign a nondisclosure agreement in order to use the DLL which is needed for me to add the capability to interface with IDEXX blood chemistry lab equipment to my veterinary management application. I called to see if I could provide the DLL to you, but they are already gone for the day. I suspect, however, that they would balk. I will, however, inquire when I speak with them again. "Leon Zandman" <NOSPAMusenet (AT) wirwar (DOT) com> wrote Quote: Also, does this indicate if one or two parameters are needed? I'm still lost as Hogan's goat!!! I need some more information. Maybe you can send me the DLL? Anyway, this next example compiles: procedure TForm1.Button1Click(Sender: TObject); var a: array of byte; v: OleVariant; begin SetLength(a,2); a[0] := 12; a[1] := 34; v := a; Maybe this helps? Greetz, Leon Back to top Jim Sawyer Guest Posted: Fri Jul 23, 2004 2:21 pm    Post subject: Re: Using a C++ Com Object with Delphi Leon - Thanks again! It's working beautifully! Jim Sawyer "Jim Sawyer" <nospam (AT) myaddress (DOT) info> wrote Quote: That both compiled and executed! I'm sending a port inquiry response back to a com port. Com ports are always a mess. So far it's not honoring my response, but that may be because I'm not sending it what it needs to see. But, thanks to you again, I'm one major step closer, getting it to execute the function. Thanks, Jim Sawyer PS - I'm only using one parameter... Also, I had to sign a nondisclosure agreement in order to use the DLL which is needed for me to add the capability to interface with IDEXX blood chemistry lab equipment to my veterinary management application. I called to see if I could provide the DLL to you, but they are already gone for the day. I suspect, however, that they would balk. I will, however, inquire when I speak with them again. "Leon Zandman" <NOSPAMusenet (AT) wirwar (DOT) com> wrote in message news:cdk2qq$rr5$1 (AT) news3 (DOT) tilbu1.nb.home.nl... Also, does this indicate if one or two parameters are needed? I'm still lost as Hogan's goat!!! I need some more information. Maybe you can send me the DLL? Anyway, this next example compiles: procedure TForm1.Button1Click(Sender: TObject); var a: array of byte; v: OleVariant; begin SetLength(a,2); a[0] := 12; a[1] := 34; v := a; Maybe this helps? 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