Cross-platform _ declspec macro usage [excellent]

Of course there is a difference, __declspec (dllexport) is used to export the symbol, that is, the DLL that defines the function; __ declspec (dllimport) is used for import, that is, to use this function.
This header file must be included by the DLL defining the function and the program using the function. When the function is included, we want to use _ declspec (dllexport) to define the function, we want to use dllimport when included by the latter. So we use
# Ifdef _ exporting
# Define class_declspec _ declspec (dllexport)
# Else
# Define class_declspec _ declspec (dllimport)
# Endif
In the DLL defining the function, the compilation option defines _ exporting, but the program using the function is not defined.
Source: http://bbs.csdn.net/topics/330169671>  

From Weizhi note (wiz)