#ifndef SOUNDDATA_H
#define SOUNDDATA_H

#include <iostream>
#include <string>
#include <vector>

namespace soundData
{

   using std::ostream;
   using std::istream;
   using std::string;
   using std::vector;

   class FeatureVector
   {
     private:
       vector<double> values_;
     public:
     //Accessors
       int count() const;
       double operator[](int i)const; // array  accesor operator
       double distanceTo( FeatureVector const& other ) const;
       // Construction & destruction:
        explicit FeatureVector( int n = 0 ); //explicit  converting constructor

   };
   class Frame
   {
    public:
        FeatureVector features;
          // Modifiers:
        friend void swap( Frame& a, Frame& b ); // this function can access the members  of class

        // Construction & destruction:
        explicit Frame( int nFeatures );

   };
   class Frames
   {
       private:
       vector<Frame> frames_;
       int            nFeaturesPerFrame_;

       public:
        // Accessors:
        int count() const;
        int nFeaturesPerFrame() const;
        Frame const& operator[]( int i ) const;

        // Modifiers:
        Frame& addFrame();
        friend void swap( Frames& a, Frames& b );

        // Construction & destruction:
        explicit Frames( int nFeaturesPerFrame = 0 );


   };

  /* void loadFrom( 
      istream& stream, 
      Frames& frames, ostream& log, 
      string const& streamName = "a text stream");*/

   void  loadFrom(
      istream& stream,
      Frames& frames,
      string const& streamName = "a text stream",
	 // ostream should also have default parameter as streamName
      ostream& log  =std::clog); //std::clog create an object for ostream

   void laodFromFile(
      string const& fileName,
      Frames& frames,
      ostream&  log =std::clog);

   //name space soundData.
}
#endif // SOUNDDATA_H

In function `_start':
undefined reference to `main'