std::runtime_error (3) - Linux Man Pages
Defined in header <stdexcept>
Defines a type of object to be thrown as exception. It reports errors that are due to events beyond the scope of the program and can not be easily predicted.
Exceptions of type std::runtime_error are thrown by the following standard library components: std::locale::locale and std::locale::combine.
In addition, the standard exception types std::range_error, std::overflow_error, std::underflow_error, std::regex_error, and std::system_error are derived from std::runtime_error.
constructor (public member function)
explicit runtime_error( const std::string& what_arg ); (1)
explicit runtime_error( const char* what_arg ); (2) (since C++11)
Constructs the exception object with what_arg as explanatory string that can be accessed through what().
Because copying std::runtime_error is not permitted to throw exceptions, this message is typically stored internally as a separately-allocated reference-counted string. This is also why there is no constructor taking std::string&&: it would have to copy the content anyway.
what_arg - explanatory string
May throw std::bad_alloc
Inherited from std::exception
destructor destroys the exception object
what returns an explanatory string