<exception>

namespace std {
    class exception;
    class bad_exception;
    typedef void (*terminate_handler)();
    typedef void (*unexpected_handler)();
    terminate_handler set_terminate(terminate_handler ph) throw();
    unexpected_handler set_unexpected(unexpected_handler ph) throw();
    void terminate();
    void unexpected();
    bool uncaught_exception();
    };

Include the standard header <exception> to define several types and functions related to the handling of exceptions.