() at the throw point.
        Similarly, it's a bad idea to use a base or member whose ordinary
        constructor(s) might throw, because, though not necessarily fatal to
        your program, you may report a different exception than intended from
        a <i>throw-expression</i> that includes construction such as: 

        <blockquote>
<pre>
throw some_exception();    
</pre>
        </blockquote>

        <p>There are various ways to avoid copying string objects when
        exceptions are copied, i