Quick Q: Vector going out of bounds without giving error
Quick A: Welcome to undefined behaviour.
Recently on SO:
Vector going out of bounds without giving error
STL vectors perform bounds checking when the
.at()member function is called, but do not perform any checks on the[]operator.When out of bounds, the
[]operator produces undefined results.

ACCU’s Overload journal of February 2018 is out. It contains the following C++ related articles.