Take time in milliseconds

Question

I have found the usleep function in unistd.h, and I thought it was useful to wait some time before every action.But I have discovered that the thread just sleeps if it it doesn't receive any signal.For example if I press a button (I'm using OpenGL but the question is more specific about time.h and unistd.h), the thread gets awaken and I'm not getting what I want. In time.h there is the sleep function that accepts an integer but an integer is too much ( I want to wait 0.3 seconds), so I use usleep. I ask if there is a function to take time in milliseconds (from any GNU or whatever library). It should work like time(), but returning milliseconds instead of seconds.Is that possibile?

Answer 1

If you have boost you can do it this way:

#include <boost/thread.hpp>

int main()
{
  boost::this_thread::sleep(boost::posix_time::millisec(2000));
  return 0;
}

This simple example, as you can see in the code, sleeps for 2000ms.

Edit:

Ok, I thought I understood the question but then I read the comments and now I'm not so sure anymore.

Perhaps you want to get how many milliseconds that has passed since some point/event? If that is the case then you could do something like:

#include <boost/chrono.hpp>
#include <boost/thread.hpp>
#include <iostream>


int main()
{
  boost::chrono::high_resolution_clock::time_point start = boost::chrono::high_resolution_clock::now();
  boost::this_thread::sleep(boost::posix_time::millisec(2000));
  boost::chrono::milliseconds ms = boost::chrono::duration_cast<boost::chrono::milliseconds> (boost::chrono::high_resolution_clock::now() - start);
  std::cout << "2000ms sleep took " << ms.count() << "ms " << "\n";
  return 0;
}

(Please excuse the long lines)