Importing an unmanaged DLL in C# when name is not known at compile time

Question

I am hoping this is a simple question but I have not been able to find the solution in my searching. I have a C# application that needs to load data from several DLLs. Each DLL is guaranteed to have the same function foo(). But I want these DLLs to be plug and play at run time. The way I usually handle DLLs (where I know the name) is using:

[DllImport("my_dll.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern int foo();

How do I do this with a dynamic string for a file name instead (e.g., "my_dll_3934.dll")? Also, there may be more than 1 dll that must be loaded that matches the same signature (e.g., "my_dll_3934.dll" and "my_dll_3935.dll").

The DLLs that will be used are generated by me but I want the end-user to just drop the DLL in as updates/new dlls become available without updating the application. I will be doing appropriate error checking and exception handling.

Thank you in advance.

Take a look at this Q&A...I think that the one that haves 11 votes would fill your requirements :) http://stackoverflow.com/questions/8836093/how-can-i-specify-a-dllimport-path-at-runtime — Hackerman, Sep 29 '16 at 17:12
I don't have a code example immediately, so I'll post this as a comment rather than a solution, but I think you'll need to explore LoadLibrary() and then GetProcAddress() to accomplish this in a dynamic scenario such as that you describe. You can pass a string to LoadLibrary, get a handle to the module, then use GetProcAddress to find the function. — David W, Sep 29 '16 at 17:13
Also do not forget that if that answer helps you, give it un up vote! — Hackerman, Sep 29 '16 at 17:14
Thank you @Hackerman. I've done the library handle/proc address on the C++ side but I couldn't seem to get it to work on C# side. The answer you suggested showed me what I needed. I have upvoted his response. — JLB, Sep 29 '16 at 19:15

score 0 · Answer 1 · edited May 23 '17 at 12:19

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Answer to my question can be found here:

How can I specify a [DllImport] path at runtime?

in the comment by user Ran. Thanks to Hackerman for pointing me to the correct solution.

edited May 23 '17 at 12:19

Community

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answered Sep 29 '16 at 19:14

JLB

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Don't do that Either delete your question or flag the question as a duplicate for moderators pointing at the other question – Scott Chamberlain Sep 29 '16 at 19:16
Sorry. Didn't know. Should I delete the answer? – JLB Sep 29 '16 at 19:19
Because I already closed your question as a duplicate I don't think it is nessesary. – Scott Chamberlain Sep 29 '16 at 19:20

Importing an unmanaged DLL in C# when name is not known at compile time

1 Answers1