std::underflow_error - Man Page

underflow_error (const char *)
underflow_error (const string &__arg)
underflow_error (const underflow_error &)=default
underflow_error (underflow_error &&)=default
underflow_error & operator= (const underflow_error &)=default
underflow_error & operator= (underflow_error &&)=default
virtual const char * what () const noexcept

Returns a C-style character string describing the general cause of the current error (the same string passed to the ctor).

Reimplemented from std::exception.

Reimplemented in std::experimental::filesystem::v1::filesystem_error, and std::filesystem::filesystem_error.