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The problem is that after you read the price using >> the endline following the price remains in the input stream. Next time you call getline, it will read an emtpy line (i.e. only the endline...

So why call it books, i.e. not book (singular).

You create an empty vector, so bvec.begin() equals bvec.end(). Dereferencing that iterator gives undefined behavior. Instead, create and initialize...