问题
I'm trying to find a online reference to see the exception safety of several std containers.
In the case of std::vector, Does it keep the state previous to the push_back call? I would presume the vector has all its objects still valid (no destructors invoked). What guarantees offer std::vector after push_back throws a std::bad_alloc exception?
回答1:
If it throws, the vector isn't changed. Even not the capacity().
According to [container.requirements.general]:
Unless otherwise specified (see 23.2.4.1, 23.2.5.1, 23.3.3.4, and 23.3.6.5) all container types defined in this Clause meet the following additional requirements:
[...]
— if an exception is thrown by a push_back() or push_front() function, that function has no effects.
来源：https://stackoverflow.com/questions/8899814/state-of-stdvector-after-stdbad-alloc