CODEWITHSUNDEEP
visual-c++dlllinker
user103981
user103981

Reputation:

Unresolved external symbol link error

I have a project where I need mouse hooks to be used, so I have added a MOUSE HOOK DLL project to my solution.On rebuild,I am getting the following errors: 

Error   3   error LNK2005: "struct HHOOK__ * MyHook" (?MyHook@@3PAUHHOOK__@@A) already defined in projdialog.obj    projdialogDlg.obj
Error   4   error LNK2005: "struct HINSTANCE__ * MyInstance" (?MyInstance@@3PAUHINSTANCE__@@A) already defined in projdialog.obj    projdialogDlg.obj
Error   5   error LNK2019: unresolved external symbol "void __cdecl Hook(void)" (?Hook@@YAXXZ) referenced in function "public: void __thiscall CProjdialogDlg::OnLButtonDown(unsigned int,class CPoint)" (?OnLButtonDown@CProjdialogDlg@@QAEXIVCPoint@@@Z)  projdialogDlg.obj
Error   6   error LNK2019: unresolved external symbol "void __cdecl Unhook(void)" (?Unhook@@YAXXZ) referenced in function "public: void __thiscall CProjdialogDlg::OnLButtonUp(unsigned int,class CPoint)" (?OnLButtonUp@CProjdialogDlg@@QAEXIVCPoint@@@Z)  projdialogDlg.obj
Error   7   fatal error LNK1120: 2 unresolved externals .\Debug/projdialog.exe

Upvotes: 1

Views: 4659

Answers (1)

WindowsPistha
WindowsPistha

Reputation: 100

1) "struct HHOOK__ * MyHook" (?MyHook@@3PAUHHOOK__@@A) already defined in projdialog.obj

Usually this error will occur , if that function is getting included twice by repeated inclusion of header files ,U can watch out for that (or) use this Linker option FORCE:MULTIPLE

2) Unresolved external symbol error. Compiler not able to find the function definitions of Hook & Unhook.

if it is defined in another file , include that header file. and add this on the top of the file where you are invoking the function. extern void __cdecl Unhook(void);

if it is a API and dll is implicitly linked. Add the .lib of the dll in additional dependencies.

Upvotes: 1

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