what is the operator be overloading here :　String8::operator const char*() const
<p>I know it is used to get the containing c string ,similar to <code>std::string.c_str().</code> But how should I use the operator? </p>

<pre><code>//android/frameworks/base/include/utils/String8.h
458 inline String8::operator const char*() const
459 {  
460     return mString;
461 }  
</code></pre>
