std::exception::what

From cppreference.com
< cpplrm; | errorlrm; | exception
virtual const char* what() const;
(until C++11)
virtual const char* what() const noexcept;
(since C++11)

Returns the explanatory string.

Parameters

(none)

Return value

Pointer to a null-terminated string with explanatory information. The pointer is guaranteed to be valid at least until the exception object from which it is obtained is destroyed, or until a non-const member function on the exception object is called.