Create a C++/CLI wrapper from a C++ native class with CStrings in them

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Hello,

I have a huge C++ native class with a lot of CStrings in them. I am trying to write a managed class using C++/CLI in order to use it in my C# interface. I am getting a lot of errors like these:

Code:

const CString TAG_DISPLAY_USER_ANONYMOUS = TEXT("");

Error:

C++

error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

error C2146: syntax error : missing ';' before identifier 'TAG_DISPLAY_USER_ANONYMOUS'

error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

error C3861: 'TEXT': identifier not found

This I checked online and is because C++/CLI doesnt support CStrings. What is the best way to go about it? Could someone please give me a proper example as well. I have read that I need another interface in between to manage the CStrings. Can anyone suggest me the best way out of this? Really stuck on this :(

Thanks.

Posted 27-Mar-14 2:49am

Mobile.Instinct

Updated 27-Mar-14 4:33am

v3

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Philippe Mori 13-May-14 18:38pm

Typically you would create a wrapper class and then use gcroot to hold pointer to navive code from the managed one.

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bling · Answer 1 · 2014-03-27T05:35:00

Solution 2

There is nothing wrong with using CString in a C++/CLI assembly.

Look in your project's DLL.h and/or StdAfx.h header files. You are probably missing a #include <afx.h> so that the compiler sees the definition for CString.

Once it compiles, you may run into problems linking. Make sure the project's Configuration Properties has the General setting "Use of MFC" set to "Use MFC in a Shared DLL" or "Use MFC in a Static Library".

Posted 27-Mar-14 5:35am

bling

Updated 27-Mar-14 5:49am

v3

Comments

Mobile.Instinct 27-Mar-14 12:41pm

I think you are right. I have tried your solution and am somehow able to make it work. Would be great if it worked through out. Shall post soon if it does. No compiler errors anymore :)

Richard MacCutchan · Answer 2 · 2014-03-27T04:23:00

Solution 1

That message is produced as a result of function definitions of the form:

C++

extern foo(int i);

which have no explicit return type. Nothing to do with CString.

Note: it would really help if you actually showed us the line(s) of code that produces the error message.

Posted 27-Mar-14 4:23am

Richard MacCutchan

Comments

Mobile.Instinct 27-Mar-14 10:33am

Updated the question. Please have a look.

Richard MacCutchan 27-Mar-14 10:41am

The compiler does not recognise CString or TEXT. You need to include the appropriate headers to define them. However, since this is C++/CLI, I don't think you can, since .NET and MFC do not mix.

Mobile.Instinct 27-Mar-14 10:43am

So is there no way out from this? I tried this: http://www.multicoreconsulting.co.uk/blog/c-snippets/how-to-call-unmanaged-cplusplus-from-csharp/ but still no luck.

Richard MacCutchan 27-Mar-14 11:03am

The way out would be to write a 'normal' C++ interface that can take the CString objects and convert them to ordinary C-type strings. You can then pass such strings into your C# code via COM or P/Invoke.