text: #pragma once
  
  #include <time.h>
  
  class CElapsedTimer {
  public:
      CElapsedTimer() { }
  
      bool is_valid() const { return m_valid; }
      void start();
      int elapsed() const;
  
  private:
      bool m_valid { false };
      struct timeval m_start_time { 0, 0 };
  };
  