LINK error: LNK2020 - Should I link the unmanaged libraries <math.h>, <stdio.h> ?

I am developing a Managed class that is a wrapper for other unmanaged classes that uses the old C++ libraries: <math.h>, <stdio.h>,<string.h>, <stdlib.h>.

My little project compiles all right, but I get this LINK error:

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LNK2020: unresolved token (0A000019) ??_7type_info@@6B@

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I did not link this files (<math.h>, <stdio.h>,…). Do I need to do this? If I need, how I can do that?

Thanks in advance.

If this appears you do not have RTTI enabled. Please do so in the Compiler Options in your project properties.

Thank you very much NoHero.
I did what you said.

I did not say before, I am developing a C++.Net Template. C++ Managed Wraaper to wrapp unmanaged code.


I had lots of LNK2019 errors and then, I ´ve applied some instructions of Microsoft: http://www.support.microsoft.com/?sc...d=2990&sid=149. Now, most of these errors have gone. But I still have link errors. Like that:

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error LNK2019: unresolved external symbol _strupr and error LNK2019: unresolved external symbol _hypot. error LNK2001: unresolved external symbol _hypot .

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Why I get these errors? Why Microsoft C++ .NET 2003 could not link properly the standard libraries <math.h>, <string.h> ???

Thanks a lot.

Eliseu.

Then you forgot to link the libraries of the default C library inside your application.

Project Properties -> Linker -> Input -> Additional Libraries -> And add msvcrt.lib for release version and msvcrtd.lib for debug version.

These libraries may also have a version suffix. Like msvcrt80.lib or something like that. I am not quite sure though, better you look them up in your Visual Studion installation directory -> VCX (X is the version number you are using) -> Libs.

NoHero, I did what you wrote me. But the linking process stills having the same errors:

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Basicas.obj : error LNK2019: unresolved external symbol _strupr referenced in function "void __cdecl LatsGMSt2sGMS(char *,int &,int &,int &,double &)" (?LatsGMSt2sGMS@@YAXPADAAH11AAN@Z)

Basicas.obj : error LNK2019: unresolved external symbol _hypot referenced in function "double __cdecl AnguloPP2(double,double,double,double)" (?AnguloPP2@@YANNNNN@Z)

Tmgeod.obj : error LNK2001: unresolved external symbol _hypot

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I did not find other versions for msvcrtd.lib in VC7\lib. Just this.

Interesting that I am using others funcions from <math.h>, <string.h>, <stdio.h> and <stdlib.h> and is ok on the linking. Do you have any idea about why some funcionts are linked and others not?

Thanks for your help.

Firstly, which version of DevStudio are you using ? There are two now : 2003 and 2005, although it shouldn't really be a problem unless you're using the Beta for 2005. Even then this shouldn't happen, but this is to just narrow things down.

Anyway, I'm including a VC++.NET (DevStudio 2003) project which does just what you're having problems with. It's a console application, created from the wizards.

And the code is in the source folder in solution explorer, CodeGuruTemp1.cpp.

I hope it helps.

Darwen.

All these functions above are within the Microsoft C Runtime, but not ANSI standard. Here is another resource on this C Runtime. Also be sure your source files using these functions are compiled as unmanaged.

Thanks Guys.

I really apreciate your help. I am not on the office now. I will come back on MOnday and I will test your sugestion. Yes NOHero, I was looking this table of LIBs today but I did not have time to test them yet.

By the way, I am using Visual Studio 2003.

I wish a fantastic happy new year to U.

Take care.

NoHero, on that link there is this option

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MSVCRT.LIB Multithreaded, dynamic link (import library for MSVCR71.DLL). Be aware that if you use the Standard C++ Library, your program will need MSVCP71.DLL to run. /MD _MT, _DLL

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It says:

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your program will need MSVCP71.DLL to run.

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What does it means:

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Any application built with Visual C++ .NET using the /MD switch will necessarily use msvcr71.dll.

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Do I need to do something about MSVCP71.DLL??? Do I need to include this someway? I ´ve tried several options to include this but is not possible. Than I think it is enough to have this file on Visual Studio Libraries...

Thanks for your help Darwen. Ive´run your project. It´s worked.

I just do not understand why i needed to change strupr(x) to
_strupr(x), or hypot for _hypot???

Do you have a clue about this?

I just read your report and it was reporting errors for _hypot et al. Actually you can remove the underscore from the start and it still works fine.

Darwen.

But for my project i get link errors if I do not use _hypot _strupr. Just for these 2. For anothers functions, I do not need to use underscore.

I ´ve put my project. See it in Basicas.cpp and TMGEOD.cpp these 2 functions.

Thank U very much.