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@mcleary

mcleary/Timer.cpp

Last active Apr 12, 2021
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C++ Timer using std::chrono
#include <iostream>
#include <chrono>
#include <ctime>
#include <cmath>
class Timer
{
public:
void start()
{
m_StartTime = std::chrono::system_clock::now();
m_bRunning = true;
}
void stop()
{
m_EndTime = std::chrono::system_clock::now();
m_bRunning = false;
}
double elapsedMilliseconds()
{
std::chrono::time_point<std::chrono::system_clock> endTime;
if(m_bRunning)
{
endTime = std::chrono::system_clock::now();
}
else
{
endTime = m_EndTime;
}
return std::chrono::duration_cast<std::chrono::milliseconds>(endTime - m_StartTime).count();
}
double elapsedSeconds()
{
return elapsedMilliseconds() / 1000.0;
}
private:
std::chrono::time_point<std::chrono::system_clock> m_StartTime;
std::chrono::time_point<std::chrono::system_clock> m_EndTime;
bool m_bRunning = false;
};
long fibonacci(unsigned n)
{
if (n < 2) return n;
return fibonacci(n-1) + fibonacci(n-2);
}
int main()
{
// std::chrono::time_point<std::chrono::system_clock> start, end;
// start = std::chrono::system_clock::now();
// Timer timer;
// timer.start();
// std::cout << "f(42) = " << fibonacci(42) << '\n';
// timer.stop();
//
// std::cout << "Time: " << timer.elapsed() << std::endl;
// end = std::chrono::system_clock::now();
// std::chrono::duration<double> elapsed_seconds = end-start;
// std::time_t end_time = std::chrono::system_clock::to_time_t(end);
// std::cout << "finished computation at " << std::ctime(&end_time)
// << "elapsed time: " << elapsed_seconds.count() << "s\n";
Timer timer;
timer.start();
int counter = 0;
double test, test2;
while(timer.elapsedSeconds() < 10.0)
{
counter++;
test = std::cos(counter / M_PI);
test2 = std::sin(counter / M_PI);
}
timer.stop();
std::cout << counter << std::endl;
std::cout << "Seconds: " << timer.elapsedSeconds() << std::endl;
std::cout << "Milliseconds: " << timer.elapsedMilliseconds() << std::endl
;
}
@Vasily-Biryukov

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@Vasily-Biryukov Vasily-Biryukov commented Jan 21, 2020

Better use std::chrono::steady_clock, because the system time (used by system_clock) can be adjusted at any moment.

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