External symbols that cannot be parsed when a third-party library lib/DLL is referenced

External symbols that cannot be parsed when a third-party library lib/DLL is referenced:
Error:
Error lnk2019: the external symbol "_ declspec (dllimport) Public: _ thiscall Add ::~ Add (void)
Unable to connect to class implementation in library lib loaded externally
Compilation can be performed through

Explanation:
Because the specified msqerror class does not use declarative _ declspec (dllexport)
The project mesquite is responsible for generating lib files from the source file, and using the third-party libraryProgramUsually, I. Add the header file containing directory (V in C/C ++, General, additional include directory :), used to include the header file,
Used in this compilation
Ii. lib and DLL files used to add links (in the linker, input, and add dependencies :).
3. specify where to find the Lib library file (in the linker, General, additional Library :)

Therefore, if an error occurs when the mesquite library is used, define # define mesquite_export _ declspec (dllexport.