How can I resolve “error LNK2019: unresolved external symbol”? [duplicate]

Answer 1

I know it is already 2 years since this question... but i run in the same situation here. Added all the header files... added the lib directories.. and keep having this error. So i added manually the lib to the Configuration Properties -> Linker -> Input -> Aditional Dependencies and all works for me.

Answer 2

You either need to link the codeproject SQLite lib to your executable, or to include the sources files in your project directly. (Which one did you do ?)

Answer 3

It happened to me more than once that I thought symbol XXX (i.e. ?close@CppSQLite3DB@@QAEXXZ) was in the import lib, while the actual symbol was __impXXX (i.e. __imp?close@CppSQLite3DB@@QAEXXZ).

The reason for the linker error is then to be found in the compilation step: the compiler will generate the ?close@CppSQLite3DB@@QAEXXZ symbol to be imported, where it should generate __imp?close@CppSQLite3DB@@QAEXXZ. This often means that the function declaration itself didn't have __declspec( dllimport ). Which may be caused by some preprocessor symbol not being defined. Or the __declspec not being there at all...

Answer 4

The compiler and linker will not link one library into another (unless one is a DLL). You need to specify both libraries (cppsqlite3.lib and your own static library) in your main project.

Answer 5

I would follow these steps:

1. think about what library or .obj file you expect the symbol to be exported by.

2. check whether it actually does export that very symbol (check character-wise). Sometimes, it's the calling convention differs.

3. check if the library you expect to contain the symbol is known to the linker - first check for the 'additional libraries', then check if the library is actually found (I mostly do this by using filemon.exe from sysinternals, and look for link.exe to open the lib file. )

After thinking a while, you may find that your library project will not export the sought for function. That function is in the database lib. You should add that lib to your main project. It's no use adding it to your static lib project.

Answer 6

Don't know if it is your case, but the imp prefix may mean that you are compiling a x64 library in a Win32 project.