We must generally assume that adding elements to a vector will invalidate every reference, pointer, or iterator that refers to a vector element.

Last week, I pointed out that putting a new element in a vector might reallocate the vector. As a result of this behavior, we must generally assume that adding elements to a vector will invalidate every reference, pointer, or iterator that refers to a vector element.

via Copying Container Elements From The C++ Library: It’s Trickier Than It Looks | Dr Dobb’s.