title: Unresolved external link errors with generated DLL in Embarcadero C++ Builder
body: <p>I am trying to use the AWS Iot SDK in Embarcadero C++ Builder which I am using the Embedded C Version of the SDK. I was trying to use a generated DLL in the RAD Studio IDE but wasn't able to input the functions needed as it was all under namespaces and classes. </p>
  
  <p>Hence why I have resolved to using the Embedded C version of the SDK as talked about in this question because of it's portability.  <a href="https://stackoverflow.com/questions/59656238/calling-dll-functions-under-a-namespace-in-rad-studio?noredirect=1#comment105504951_59656238">Calling DLL Functions under a namespace in RAD Studio</a></p>
  
  <p>With the Embedded C version of the SDK, I have again generated it to be a DLL file where I have used the code below to export the data structures and functions with this example below:</p>
  
  <pre><code>#ifdef PUBSNUB_EXPORTS
  #define PUBSNUB_API __declspec(dllexport)
  #else
  #define PUBSNUB_API __declspec(dllimport)
  #endif
  
  PUBSNUB_API IoT_Error_t aws_iot_mqtt_publish(AWS_IoT_Client* pClient, const char* pTopicName, uint16_t topicNameLen,
      IoT_Publish_Message_Params* pParams); 
  
  PUBSNUB_API IoT_Error_t aws_iot_mqtt_subscribe(AWS_IoT_Client *pClient, const char *pTopicName, uint16_t topicNameLen,
                                     QoS qos, pApplicationHandler_t pApplicationHandler, void *pApplicationHandlerData);
  </code></pre>
  
  <p>When I try to call these functions in RAD studio, I get the following errors, even with the generated lib file as instructed copied in the project folder. If I call these functions in a Visual Studio project, it will work completely fine. </p>
  
  <pre><code>[ilink32 Error] Error: Unresolved external '_iotClientConnectParamsDefault' referenced from C:\MICRO PLUS\RELEASE\MAINFORM.OBJ
  [ilink32 Error] Error: Unresolved external '_iotClientInitParamsDefault' referenced from C:\MICRO PLUS\RELEASE\MAINFORM.OBJ
  [ilink32 Error] Error: Unresolved external '_aws_iot_mqtt_publish' referenced from C:\MICRO PLUS\RELEASE\MAINFORM.OBJ
  [ilink32 Error] Error: Unable to perform link
  </code></pre>