Java is memory safe, at a runtime cost (sometimes that cost is trivial, sometimes it isn't). It will insert a check every time you do a pop. C++ is not. It's a

Java is memory safe, at a runtime cost (sometimes that cost is trivial, sometimes it isn't). It will insert a check every time you do a pop. C++ is not. It's a precondition of calling pop_back() that the vector is not empty. It will not insert a runtime check - it leaves you to decide whether one is needed. Your C++ toolchain will probably have an option to make (usually debug) builds check and complain if you actually call pop_back() on an empty vector.