linkage error
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I have a lib and its corresponding header file in C or C++ that I want to use it in Visual C++.net. The header file has a structure like this: Reader.h: class AFX_EXT_CLASS Reader { . . . }; extern "C" AFX_EXT_API Reader * CreateReader(); There is no problem using the class but I can't use the CreateReader() function. There are 2 linkage errors: LNK2028, LNK2019. Can you help me using this function please? Thanks in advance
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I have a lib and its corresponding header file in C or C++ that I want to use it in Visual C++.net. The header file has a structure like this: Reader.h: class AFX_EXT_CLASS Reader { . . . }; extern "C" AFX_EXT_API Reader * CreateReader(); There is no problem using the class but I can't use the CreateReader() function. There are 2 linkage errors: LNK2028, LNK2019. Can you help me using this function please? Thanks in advance
Its probably because the calling conventions used where the function is declared and where the function is used are different. How is AFX_EXT_API defined? If it is defined as
__declspec(dllexport), make it__stdcall __declspec(dllexport)Or rather, simply make itextern "C" AFX_EXT_API Reader* __stdcall CreateReader();«_Superman_» I love work. It gives me something to do between weekends.
modified on Tuesday, August 18, 2009 5:57 AM
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Its probably because the calling conventions used where the function is declared and where the function is used are different. How is AFX_EXT_API defined? If it is defined as
__declspec(dllexport), make it__stdcall __declspec(dllexport)Or rather, simply make itextern "C" AFX_EXT_API Reader* __stdcall CreateReader();«_Superman_» I love work. It gives me something to do between weekends.
modified on Tuesday, August 18, 2009 5:57 AM
I don't have any access to the lib file. I only use it. You mean I only change it in the header file?! Is it possible? Besides there is no __declspec(dllexport). It is declared exactly as I wrote: extern "C" AFX_EXT_API Reader* CreateReader(); Besides I use it with /clr. Thanks
modified on Tuesday, August 18, 2009 6:08 AM
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I don't have any access to the lib file. I only use it. You mean I only change it in the header file?! Is it possible? Besides there is no __declspec(dllexport). It is declared exactly as I wrote: extern "C" AFX_EXT_API Reader* CreateReader(); Besides I use it with /clr. Thanks
modified on Tuesday, August 18, 2009 6:08 AM
It is not enough to simply change it in the header file, unless you know which calling convention was used. You can try and use different calling conventions like
__cdecland__stdcall.«_Superman_» I love work. It gives me something to do between weekends.
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It is not enough to simply change it in the header file, unless you know which calling convention was used. You can try and use different calling conventions like
__cdecland__stdcall.«_Superman_» I love work. It gives me something to do between weekends.
You mean when I want to call it, for example in one function in my own application I use "__cdecl" before calling? like this?: Reader* m_pReader=__cdecl CreateReader();
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You mean when I want to call it, for example in one function in my own application I use "__cdecl" before calling? like this?: Reader* m_pReader=__cdecl CreateReader();
No. I mean in the header file.
«_Superman_» I love work. It gives me something to do between weekends.
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No. I mean in the header file.
«_Superman_» I love work. It gives me something to do between weekends.
I change the header file from: extern "C" AFX_EXT_API Reader * CreateReader(); to: extern "C" AFX_EXT_API Reader * __stdcall CreateReader(); and also: extern "C" AFX_EXT_API Reader * __cdecl CreateReader(); but it doesn't work.The same errors occur. Should I do anything while calling the function? I include the header file and call the function as a usual ones.
modified on Tuesday, August 18, 2009 7:04 AM
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I have a lib and its corresponding header file in C or C++ that I want to use it in Visual C++.net. The header file has a structure like this: Reader.h: class AFX_EXT_CLASS Reader { . . . }; extern "C" AFX_EXT_API Reader * CreateReader(); There is no problem using the class but I can't use the CreateReader() function. There are 2 linkage errors: LNK2028, LNK2019. Can you help me using this function please? Thanks in advance
Did ya read the msdn for the errors? http://msdn.microsoft.com/en-us/library/799kze2z(VS.80).aspx I guess your CreateReader() implementation is missing or falsly decorated. A Hint: I hope you are not creating objects in the dll and try to destroy it in the app. This can leads to strange errors. Such interfaces are better "native" as integer or LPCSTR pointers!!! It is hard to tell :((
Press F1 for help or google it. Greetings from Germany
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Did ya read the msdn for the errors? http://msdn.microsoft.com/en-us/library/799kze2z(VS.80).aspx I guess your CreateReader() implementation is missing or falsly decorated. A Hint: I hope you are not creating objects in the dll and try to destroy it in the app. This can leads to strange errors. Such interfaces are better "native" as integer or LPCSTR pointers!!! It is hard to tell :((
Press F1 for help or google it. Greetings from Germany
I finally could solve the problem by changing "\properties\linker\input\Additional Dependences\". It compiles well and there is no linkage error anymore but I get another error while running the project: "The specified module could not be found (Exception from HRESULT:0x8007007E)" The error happens in Application.Run in program.cs, but not at the time of loading the form, but it happens when I want to make an object from my class, even when I don't use that specific function. Besides my dll is in Visual C++.Net and I'm calling it from C#.Net. Could you please help me? Thanks in advance
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I finally could solve the problem by changing "\properties\linker\input\Additional Dependences\". It compiles well and there is no linkage error anymore but I get another error while running the project: "The specified module could not be found (Exception from HRESULT:0x8007007E)" The error happens in Application.Run in program.cs, but not at the time of loading the form, but it happens when I want to make an object from my class, even when I don't use that specific function. Besides my dll is in Visual C++.Net and I'm calling it from C#.Net. Could you please help me? Thanks in advance
some COM-Error are a pain -most- if they arent documented by MS :mad: i found after googling: http://msdn.microsoft.com/en-us/library/e74a18c4(VS.71).aspx you should narrow to the problem, maybe your COM object GUID isnt properly registed or the instance cant be launched because missing dlls. Most common mixed debug and release builds. Have a lot of fun ... :doh:
Press F1 for help or google it. Greetings from Germany