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POLoading a C++ DLL in C#
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copied!<p>I am trying to use a DLL that was writen in C++ but my application is in C#</p> <p>The DLL is from another company but they have supplied an SDK for their software.</p> <p>They give an example of how to load their DLL in C++ but I need to adapt it to C#.</p> <p>Below is their instructions of how to do it in C++</p> <p>MarkEzd.dll file is Dynamic Link Library.</p> <p>MarkEzdDll.h is header file of the exports function in MarkEzd.dll</p> <p>The calling way of MarkEzd.dll is explicitly link. Developer needs to load and free MarkEzd.dll by calling Windows API function.</p> <p>The steps are as follows.</p> <ol> <li><p>Call Windows’ API function LoadLibrary() to load DLL dynamically; </p></li> <li><p>Call Windows’ API function GetProcAddrress() to get the pointer of the functions in the DLL and use the function pointer to finish the work;</p></li> <li><p>Call Windows’ API function FreeLibrary() to release library when you do not use DLL or the program ends.</p></li> </ol> <p>Below is the example they have provided.</p> <p>Step 2. Program software for calling markezd.dll. a) First step : Dynamic Load MarkEzd.dll</p> <pre><code>HINSTANCE hEzdDLL = LoadLibrary(_T("MarkEzd.dll")); </code></pre> <p>b) Second step: get the pointer of the function to be called</p> <pre><code>lmc1_Initial=(LMC1_INITIAL)GetProcAddress(hEzdDLL, _T("lmc1_Initial")); lmc1_Close=(LMC1_CLOSE)GetProcAddress(hEzdDLL, _T("lmc1_Close")); lmc1_LoadEzdFile=(LMC1_LOADEZDFILE)GetProcAddress(hEzdDLL,_T("lmc1_LoadEzdFile")); lmc1_Mark=(LMC1_MARK)GetProcAddress(hEzdDLL,_T("lmc1_Mark")); </code></pre> <p>c) Third step: Call the function</p> <p>1） Initialization lmc1 board: <code>lmc1_Initial()</code>.<br> 2） Open test.ezd: <code>lmc1_LoadEzdFile(_T(“test.ezd”))</code>.<br> 3） Call lmc1_Mark() for machining: <code>lmc1_Mark()</code>.<br> 4） Close lmc1 board: <code>lmc1_Close()</code>. </p> <p>d) Fourth step, Release markezd.dll: <code>FreeLibrary(hEzdDLL)</code></p> <p>Bellow is the descriptions of the commands.</p> <p>lmc1_Initial<br> INTENTION: initialize lmc1 control board<br> DEFINITION: <code>int lmc1_Initial(TCHAR* strEzCadPath, BOOL bTestMode, HWND hOwenWnd)</code><br> strEzCadPath: the full path where ezcad2.exe exists<br> bTestMode Whether in test mode or not<br> hOwenWnd: The window that has the focus. It is used to check the user’s stop messages. DESCRIPTION: you must first call lmc1¬_Initial before other function in program.<br> RETURN VALUE: common error code </p> <p>lmc1_Close<br> INTENTION: Close lmc1 board<br> DEFINITION: <code>int lmc1_Close();</code><br> DESCRIPTION: you must call lmc1_Close to close the lmc1 board when exit program.<br> RETURN VALUE: common error code </p> <p>lmc1_LoadEzdFile<br> INTENTION: open the appointed ezd file, and clear all the object in database.<br> DEFINITION: <code>int lmc1_LoadEzdFile(TCHAR* strFileName);</code><br> DESCRIPTION: this function can open an ezd file that was build by user as a template. User need not set process parameters, because they will be loaded in from the template file.<br> RETURN VALUE: common error code </p> <p>lmc1_Mark<br> INTENTION: mark all the data in database<br> DEFINITION: <code>int lmc1_Mark(BOOL bFlyMark);</code><br> bFlyMark= TRUE // mark on fly<br> DISCRIPTION: Begin to mark by calling this function after loading ezd file using lmc1_LoadEzdFile. The function will not return back until marking complete.<br> RETURN VALUE: common error code </p> <p>They also explain how to set up VS6.0</p> <ol> <li>Choose “Microsoft Visual C++ 6.0” when install visual studio, and click “Change Option”.</li> <li>Choose “VC++ MFC and Template Libraries” and click “Change Option”.</li> <li>Choose “MS Foundation Class Libraries” and click “change option”.</li> <li>Choose the options as following picture, and click “OK”.</li> <li>Open the project, choose menu Project->Settings. Choose “C/C++”, add “UNICODE” and delete “MCBS” in “Preprocessor definitions”</li> <li>Choose “Link”, select “Output” in Category, and add “wWinMainCRTStartup” in “Entry-point symbol”</li> <li>Change all “char” to “TCHAR” in source code.</li> <li>Change all character string included by double quotation marks “…” to _T(“…”)</li> <li>Compile and link the project again.</li> </ol> <p>most of the functions return an integer code of 0 for success.</p> <p>Would this be correct?</p> <pre><code>using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Runtime.InteropServices; namespace Start_Mark { public partial class Form1 : Form { [DllImport("kernel32.dll")] public static extern IntPtr LoadLibrary(string dllToLoad); [DllImport("kernel32.dll")] public static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName); [DllImport("kernel32.dll")] public static extern bool FreeLibrary(IntPtr hModule); [DllImport("MarkEzd.dll")] [return: MarshalAs(UnmanagedType.I2)] public static extern int lmc1_Initial(string strEzCadPath, bool bTestMode, IntPtr hOwenWnd); [DllImport("MarkEzd.dll")] [return: MarshalAs(UnmanagedType.I2)] public static extern int lmc1_Close(); [DllImport("MarkEzd.dll")] [return: MarshalAs(UnmanagedType.I2)] public static extern int lmc1_LoadEzdFile(string strFileName); [DllImport("MarkEzd.dll")] [return: MarshalAs(UnmanagedType.I2)] public static extern int lmc1_Mark(bool bFlyMark); public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { IntPtr hEzdDLL = LoadLibrary("MarkEzd.dll"); IntPtr iplmc1_Initial = GetProcAddress(hEzdDLL, "lmc1_Initial"); IntPtr iplmc1_Close = GetProcAddress(hEzdDLL, "lmc1_Close"); IntPtr iplmc1_LoadEzdFile = GetProcAddress(hEzdDLL, "lmc1_LoadEzdFile"); IntPtr iplmc1_Mark = GetProcAddress(hEzdDLL, "lmc1_Mark"); int intlmc1_Initial=lmc1_Initial("c:\temp", false, hEzdDLL); if (intlmc1_Initial > 0) { return; } int intlmc1_LoadEzdFile = lmc1_LoadEzdFile("c:\temp\test.ezd"); if (intlmc1_LoadEzdFile > 0) { return; } int intlmc1_Mark = lmc1_Mark(true); if (intlmc1_Mark > 0) { return; } int intlmc1_Close = lmc1_Close(); if (intlmc1_Close > 0) { return; } FreeLibrary(hEzdDLL); } } } </code></pre>

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