bla.cpp

#include <string>
using namespace std;

#ifndef MEDIUM_H
#define MEDIUM_H
class Medium
 {
  public:
   string titel;
   bool ausleihstatus;
   virtual string getTyp() const =0;
 };
#endif // MEDIUM_H

#ifndef CD_H
#define CD_H
class CD : public Medium
 {
  private:
   unsigned int spieldauer;
  public:
   CD(void);
   string getTyp() const;
 };
#endif // CD_H

CD::CD(void)
{
 
}

string CD::getTyp()
 {
  return "CD";
 }