How to import C++ methods in C#

Pranav Thakur

Hi,
I have coded few methods in C++ language. These methods are to be used in C#.NET . I guess I need to convert the .CPP file(C++ code) into DLL and then import the methods in C#. Can any one give an idea how to convert .CPP file into DLL and then use that DLL in C#.
Thanks.

5 Replies

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Pranav Thakur17y ago
I have created an unmanaged C++ DLL and tried to call its method in C#.NET as : using System.Runtime.InteropServices; public partial class CDLL : System.Web.UI.Page { [DllImport("C:\\Project1\\TestProject\\Debug\\TestProject.dll", EntryPoint = "testMethod", ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)] public static extern void testMethod(); protected void Page_Load(object sender, EventArgs e) { testMethod(); } } After running the above code i am getting error like : Unable to find an entry point named 'testMethod' in DLL 'C:\Project1\TestProject\Debug\TestProject.dll'. Can any one suggest how to run the above code successfully. Thanks.
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Sam Hobbs17y ago
If you need to have a type library, then you don't want a regular DLL; you need a COM object. If your C++ project is a regular DLL project, then you must use a DllImport attribute to call the function in the DLL.
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Sam Hobbs17y ago
I doubt that you want to build a static library; a static library is not a DLL, correct? You need to create a DLL project and the new project will have starter souce code. Be sure that the function you create has __declspec(dllexport) on it, but the generated source codw will show how how to do that.

Or you could create a COM object. That will require more time to learn but it will be more flexible.
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Pranav Thakur17y ago
Thanks for your reply.
I followed the steps as you suggested but I could not add the created DLL into my project as reference.
I made a Win32 project and converted the exe(C++ code) into DLL.
I opened a new Visual Studio C#.NET project and tried to include the above DLL but I am getting error as :
A refernce to 'C:\application\test.dll' could not be added. No type libraries were found in the component.
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Kirtan Patel17y ago
Friend ,

You need to make a Win32 Project, and in the dialog that comes up choose DLL.

Don't make a MFC DLL unless your specifically targeting MFC, they aren't a normal DLL

Check the radio button for Static Library.

Paste All Your Code Hit compile You will Get DLL File :)

if my answer helped you please check "Do you like this answer " :)

if any problem occurred feel free to tell me :)

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