title: How to convert v8::String to const char *
body: <p>i have this function in dll</p>
  
  <pre><code>static COMMANDERDLL_API int InsertCodeBar(const char* pszBuffer);
  </code></pre>
  
  <p>in my node addon i have this function</p>
  
  <pre><code>void InsertCodeBarWrapper(const FunctionCallbackInfo&lt;Value&gt;&amp; args){
      Isolate* isolate = args.GetIsolate();
  
      Local&lt;Function&gt; cb = Local&lt;Function&gt;::Cast(args[1]);
      Local&lt;String&gt; bar = args[0]-&gt;ToString();
      const unsigned argc = 1;
      Local&lt;Value&gt; argv[argc] = { CSGPCommander::InsertCodeBar(bar) };
      cb-&gt;Call(isolate-&gt;GetCurrentContext()-&gt;Global(), argc, argv);
  }
  </code></pre>
  
  <p>when i try compile, node-gyp return error: "cannot convert argument 1 from 'v8::Local' to 'const char *'</p>
  
  <p><strong>how to convert v8::String to const char *?</strong></p>