What is the best, most accurate timer in C++?

Question

What is the best, most accurate timer in C++?

Answer 1

In C++11 you can portably get to the highest resolution timer with:

#include <iostream>
#include <chrono>
#include "chrono_io"

int main()
{
    typedef std::chrono::high_resolution_clock Clock;
    auto t1 = Clock::now();
    auto t2 = Clock::now();
    std::cout << t2-t1 << '\n';
}

Example output:

74 nanoseconds

"chrono_io" is an extension to ease I/O issues with these new types and is freely available here.

There is also an implementation of <chrono> available in boost (might still be on tip-of-trunk, not sure it has been released).

Answer 2

The answer to this is platform-specific. The operating system is responsible for keeping track of timing and consequently, the C++ language itself provides no language constructs or built-in functions for doing this.

However, here are some resources for platform-dependent timers:

• Windows API - SetTimer: http://msdn.microsoft.com/en-us/library/ms644906(v=vs.85).aspx
• Unix - setitimer: http://linux.die.net/man/2/setitimer

A cross-platform solution might be boost::asio::deadline_timer.