extern here indicates that const char libxbee_revision[] is defined in another file (usually c/cpp). This way the variable will be available globally. (For example, if there is const char libxbee_revision[] in a.cpp, if b.cpp wants to use this array in a.cpp, just extern const char libxbee_revision[] can be used)
From the writing point of view, EXPORT is a macro. Without looking at the definition of this macro, you don't know what it represents. It is possible that the definition of this macro is empty and only serves to mark the variable.
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extern here indicates that
const char libxbee_revision[]is defined in another file (usually c/cpp). This way the variable will be available globally. (For example, if there isconst char libxbee_revision[]in a.cpp, if b.cpp wants to use this array in a.cpp, justextern const char libxbee_revision[]can be used)From the writing point of view, EXPORT is a macro. Without looking at the definition of this macro, you don't know what it represents. It is possible that the definition of this macro is empty and only serves to mark the variable.
Please Google "C/C++ export extern" !