title: Linker Error: Unresolved external (C++ Builder 6.0)
body: <p>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:</p>
  
  <pre><code>[Linker Error] Unresolved external"__fastcall Idmultipartformdata::TIdMultipartFormDataStream()" referenced from C:\Users\Admin\Documents\ProjCB6\Unit1.obj.
  </code></pre>
  
  <p>Then; How I can do for resolved this problem? Thanks in advance!</p>
  
  <p>Here leave used source code =></p>
  
  <pre><code>void HTTP()
  {
  
        TStringStream  *response=new  TStringStream("");
        TIdMultiPartFormDataStream *stream=new TIdMultiPartFormDataStream(); 
        TIdHTTP  *IdHTTP1 = new TIdHTTP(NULL); 
  
    try 
    { 
  
          IdHTTP1-&gt;Request-&gt;ContentType=stream-&gt;RequestContentType; 
          stream-&gt;AddFormField("file1","doc");
          stream-&gt;AddFile("file1","c:\\3.doc","doc"); 
          stream-&gt;Position = 0;
          IdHTTP1-&gt;Post("http://172.16.8.186/doc/up.php",stream,response);
          Memo1-&gt;Lines-&gt;LoadFromStream(response);
          response-&gt;Free();
          stream-&gt;Free();
          IdHTTP1-&gt;Free();
  
  
    } 
    catch(...) 
    { 
           response-&gt;Free();
          stream-&gt;Free();
          IdHTTP1-&gt;Free();
  
    }
  }
  </code></pre>