 will
        occur if the argument passes a wider character type than the underlying sequence.
        These overloads allow a normal narrow character C string literal to be used
        as an argument, even when the underlying character type of the expression
        being matched may be something more exotic such as a Unicode character type.
      </p>
<a name="boost_regex.match_results.prefix"></a><pre class="programlisting"><span class="identifier">const_reference</span> <span class="identifier">prefix