You hold a `T*` into a `std::vector ` and then call `v.push_back` within capacity (no reallocation). The pointer is:

Always invalidated by any push_back, because the vector may reallocate even when capacity is not exceeded.

Still valid; pointers only invalidate on reallocation (or erase/pop at/before the element).

Invalidated only if T is a trivial type, since trivial types are relocated bytewise during a push_back.

Invalidated because push_back copies the whole buffer to a new backing store regardless of the capacity.

Multiple ChoiceBeginner 45s

vector reserve and pointer stability

You hold a `T*` into a `std::vector<T>` and then call `v.push_back` within capacity (no reallocation). The pointer is:

Options

1Always invalidated by any push_back, because the vector may reallocate even when capacity is not exceeded.
2Still valid; pointers only invalidate on reallocation (or erase/pop at/before the element).
3Invalidated only if T is a trivial type, since trivial types are relocated bytewise during a push_back.
4Invalidated because push_back copies the whole buffer to a new backing store regardless of the capacity.

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