ifstream

 // [27.8.1.5] Template class basic_ifstream
  /**
   *  @brief  Controlling input for files.
   *  @ingroup io
   *
   *  This class supports reading from named files, using the inherited
   *  functions from std::basic_istream.  To control the associated
   *  sequence, an instance of std::basic_filebuf is used, which this page
   *  refers to as @c sb.
   */
  template<typename _CharT, typename _Traits>
    class basic_ifstream : public basic_istream<_CharT, _Traits>
    {
    public:
      // Types:
      typedef _CharT 					char_type;
      typedef _Traits 					traits_type;
      typedef typename traits_type::int_type 		int_type;
      typedef typename traits_type::pos_type 		pos_type;
      typedef typename traits_type::off_type 		off_type;

      // Non-standard types:
      typedef basic_filebuf<char_type, traits_type> 	__filebuf_type;
      typedef basic_istream<char_type, traits_type>	__istream_type;

    private:
      __filebuf_type	_M_filebuf;

    public:
      // Constructors/Destructors:
      /**
       *  @brief  Default constructor.
       *
       *  Initializes @c sb using its default constructor, and passes
       *  @c &sb to the base class initializer.  Does not open any files
       *  (you haven't given it a filename to open).
       */
      basic_ifstream() : __istream_type(), _M_filebuf()
      { this->init(&_M_filebuf); }

      /**
       *  @brief  Create an input file stream.
       *  @param  s  Null terminated string specifying the filename.
       *  @param  mode  Open file in specified mode (see std::ios_base).
       *
       *  @c ios_base::in is automatically included in @a mode.
       *
       *  Tip:  When using std::string to hold the filename, you must use
       *  .c_str() before passing it to this constructor.
       */
      explicit
      basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
      : __istream_type(), _M_filebuf()
      {
	this->init(&_M_filebuf);
	this->open(__s, __mode);
      }

string chemin = "ton_chemin";
ifstream monFlux(chemin.c_str())
{

}