Linker Error: Unresolved external (C++ Builder 6.0)

Question

I have a routine in C++ Builder 6 that send a file to webserver via HTTP Post, and when compile the project show these error messages from Linker:

[Linker Error] Unresolved external"__fastcall Idmultipartformdata::TIdMultipartFormDataStream()" referenced from C:\Users\Admin\Documents\ProjCB6\Unit1.obj.

Then; How I can do for resolved this problem? Thanks in advance!

Here leave used source code =>

void HTTP()
{

      TStringStream  *response=new  TStringStream("");
      TIdMultiPartFormDataStream *stream=new TIdMultiPartFormDataStream(); 
      TIdHTTP  *IdHTTP1 = new TIdHTTP(NULL); 

  try 
  { 

        IdHTTP1->Request->ContentType=stream->RequestContentType; 
        stream->AddFormField("file1","doc");
        stream->AddFile("file1","c:\\3.doc","doc"); 
        stream->Position = 0;
        IdHTTP1->Post("http://172.16.8.186/doc/up.php",stream,response);
        Memo1->Lines->LoadFromStream(response);
        response->Free();
        stream->Free();
        IdHTTP1->Free();


  } 
  catch(...) 
  { 
         response->Free();
        stream->Free();
        IdHTTP1->Free();

  }
}

Answer 1

C++Builder 6 shipped with Indy 8. TIdMultipartFormDataStream was introduced in Indy 9. The fact that your code compiles at all means that your project is using Indy 9 or Indy 10 header files, but the project might have a reference to the older Indy 8 package instead of the nwer Indy 9/10 package(es). Make sure that you have completely wiped out Indy 8 from your BCB6 installation if you have upgraded to Indy 9 or later, and also make sure that your project contains references to the correct Indy package(s) for that version of Indy.