If you want to make AMX Mod X plugins you will need to learn a language called PAWN. See
http://www.compuphase.com/pawn/pawn.htm for more details
Of course PAWN is not widely used for other things, so C++ could be useful for your future. But if the book you have covers Visual Basic, C, and C++ and is called a "study guide," you will probably want to buy a better book.
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