C++ Timer Class

Just thought I'd shove this somewhere public as it's probably useful for someone.

Earlier today I had a problem where boost::timer was always returning zero. The cause was boost::timer uses std::clock which only returns the elapsed CPU time. If you use sleep(), std::clock won't update!

So here's a little class that returns the elapsed time since the timer was instantiated (or restarted) which works with sleep().

 Copyright (C) 2011 by Luke Benstead  
   
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 of this software and associated documentation files (the "Software"), to deal  
 in the Software without restriction, including without limitation the rights  
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell  
 copies of the Software, and to permit persons to whom the Software is  
 furnished to do so, subject to the following conditions:  
   
 The above copyright notice and this permission notice shall be included in  
 all copies or substantial portions of the Software.  
   
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 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  
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 THE SOFTWARE.  
   
 #ifndef TIMER_H_INCLUDED  
 #define TIMER_H_INCLUDED  
   
 #include <sys/time.h>  
   
 class Timer {  
 public:  
   Timer():  
     start_time_(now()) {  
   }  
   
   void restart() {  
     start_time_ = now();  
   }  
   
   double elapsed() const {  
     double t = now();  
   
     return double(t - start_time_);  
   }  
   
 private:  
   double now() const {  
     timeval t;  
     gettimeofday(&t, NULL);  
     return t.tv_sec + (t.tv_usec / 1000000.0);  
   }  
   
   double start_time_;  
 };  
   
 #endif // TIMER_H_INCLUDED  
   

Yeah I know, it's basic and anyone could've written it, but still might save someone 5 minutes :)