log4cpp::Category::xxx() do accept c_str()

Just got to know that in order to log a value of boost::filesystem::path with log4cpp, it is just as simple as follows:

   Category *pRoot = NULL;
   PropertyConfigurator::configure("log4c.properties");
   pRoot = &(Category::getRoot());

   path targetPath("./the_path");
   pRoot->info("%s", targetPath.c_str());

Assuming I have the following content in log4c.properties:

   log4cpp.rootCategory=DEBUG, rootAppender

   log4cpp.appender.rootAppender=ConsoleAppender
   log4cpp.appender.rootAppender.layout=PatternLayout
   log4cpp.appender.rootAppender.layout.ConversionPattern=%d [%p] %m%n

   ...

But before I got to know this, I heard there are people mention that the conversion from c_str() to const char* would not be straightforward. And it would require wcstombs() to do the conversion, thus I come out this:

   ...

   char pathName[50];
   memset(pathName, '\0', sizeof(pathName));
   wcstombs(pathName, targetPath.wstring().c_str(), sizeof(targetPath.native().length()));
   ...

Is this what they mean? Or I misunderstood something? No worry, log4cpp::Category::xxx() do accept c_str().