std::ios_base::event (3) - Linux Manuals
std::ios_base::event: std::ios_base::event
NAME
std::ios_base::event - std::ios_base::event
Synopsis
enum event {erase_event, imbue_event, copyfmt_event};
Specifies the event type which is passed to functions registered by register_callback() on specific events. The following constants are defined:
Constant      Explanation
erase_event   issued on ~ios_base() or basic_ios::copyfmt() (before the copy of members takes place)
imbue_event   issued on imbue()
copyfmt_event issued on basic_ios::copyfmt() (after the copy of members takes place, but before the exception settings are copied)
Example
 This section is incomplete
 Reason: no example