cpp/container/forward list/before begin

Returns an iterator to the element before the first element of the container. This element acts as a placeholder, attempting to access it results in undefined behavior. The only usage cases are in functions insert_after, emplace_after, erase_after, splice_after and the increment operator: incrementing the before-begin iterator gives exactly the same iterator as obtained from begin/cbegin.

Parameters
(none)

Return value
Iterator to the element before the first element.

Complexity
Constant.