Why to put last statement in loops for fetching classes in C++?

So I'm a bit confused about this section in C++ Primer 5th of Lipmann. Here's the sample code: http://ift.tt/2v5AlKL The author refered that the last statement before ending "if" is used to perform the last transaction. I don't get it at all, when I try to put a comment mark beside it, nothing happend, the program still works. I'm really sorry to bother you if this is obvious because I'm extremely new in programming. Any idea or example of this logical path would be highly appreciated