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POExplicit Loading of DLL
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  1. POExplicit Loading of DLL
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    copied!<p>I'm trying to explicitly link with a DLL. No other resources is available except the DLL file itself and some documentation about the classes and its member functions.</p> <p>From the documentation, each class comes with its own </p> <ol> <li>member typedef<br> example: <code>typedef std::map&lt;std::string,std::string&gt; Server::KeyValueMap, typedef std::vector&lt;std::string&gt; Server::String Array</code></li> <li>member enumeration<br> example: <code>enum Server::Role {NONE,HIGH,LOW}</code></li> <li>member function<br> example: <code>void Server::connect(const StringArray,const KeyValueMap), void Server::disconnect()</code></li> </ol> <p>Implementing the codes from google search, i manage to load the dll can call the disconnect function..</p> <p>dir.h </p> <pre><code>LPCSTR disconnect = "_Java_mas_com_oa_rollings_as_apiJNI_Server_1disconnect@20"; LPCSTR connect = "_Java_mas_com_oa_rollings_as_apiJNI_Server_1connect@20"; </code></pre> <p>I got the function name above from depends.exe. Is this what is called decorated/mangled function names in C++?</p> <p>main.cpp </p> <pre><code>#include &lt;iostream&gt; #include &lt;windows.h&gt; #include &lt;tchar.h&gt; #include "dir.h" typedef void (*pdisconnect)(); int main() { HMODULE DLL = LoadLibrary(_T("server.dll")); pdisconnect _pdisconnect;` if(DLL) { std::cout&lt;&lt; "DLL loaded!" &lt;&lt; std::endl; _disconnect = (pdisconnect)GetProcAddress(DLL,disconnect); if(_disconnect) { std::cout &lt;&lt; "Successful link to function in DLL!" &lt;&lt; std::endl; } else { std::cout&lt;&lt; "Unable to link to function in DLL!" &lt;&lt; std::endl; } } else { std::cout&lt;&lt; "DLL failed to load!" &lt;&lt; std::endl; } FreeLibrary (DLL); return 0;} </code></pre> <p>How do i call (for example) the <strong><em>connect</em></strong> member function which has the parameter datatype declared in the dll itself? </p> <p><strong>Edit</strong></p> <p>more info:</p> <ul> <li>The DLL comes with an example implementation using Java. The Java example contains a Java wrapper generated using SWIG and a source code.</li> <li>The documentation lists all the class, their member functions and also their datatypes. According to the doc, the list was generated from the C++ source codes.(??)</li> <li>No other info was given (no info on what compiler was used to generate the DLL)</li> </ul> <p>My colleague is implementing the interface using Java based on the Java example given, while I was asked to implement using C++. The DLL is from a third party company. </p> <p>I'll ask them about the compiler. Any other info that i should get from them?</p> <p>I had a quick read through about JNI but i dont understand how it's implemented in this case.</p> <p><strong>Update</strong></p> <p>i'm a little confused... (ok, ok... very confused)</p> <ol> <li>Do i call(GetProcAddress) each public member function separately only when i want to use them? </li> <li>Do i create a dummy class that imitates the class in the dll. Then inside the class definition, i call the equivalent function from the DLL? (Am i making sense here?) fnieto, is this what you're showing me at the end of your post? </li> <li>Is it possible to instantiate the whole class from the DLL?</li> </ol> <p>I was trying to use the connect function described in my first post. From the Depends.exe DLL output,</p> <ul> <li>std::map // KeyValueMap has the following member functions: <strong><em>del, empty, get, has_1key,set</em></strong></li> <li>std::vector // StringArray has the following member functions: <strong><em>add, capacity, clear, get, isEMPTY, reserve, set, size</em></strong> </li> </ul> <p>which is different from the member functions of map and vector in my compiler (VS 2005)...</p> <p>Any idea? or am i getting the wrong picture here...</p>
 

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