//On windows.
#include<windows.h>
Sleep(milliseconds);

//On linux.
#include<unistd.h>
unsigned int microsecond = 1000000;
usleep(3 * microsecond);//sleeps for 3 second

// c++ 11 for high resulution.

#include <chrono>
#include <thread>

int main() {
    using namespace std::this_thread; // sleep_for, sleep_until
    using namespace std::chrono; // nanoseconds, system_clock, seconds

    sleep_for(nanoseconds(10));
    // or 
    sleep_until(system_clock::now() + seconds(1));
}

// C++ 14 for high resuluton.

#include <chrono>
#include <thread>

int main() {
    using namespace std::this_thread;     // sleep_for, sleep_until
    using namespace std::chrono_literals; // ns, us, ms, s, h, etc.
    using std::chrono::system_clock;

    sleep_for(10ns);
  	// or
    sleep_until(system_clock::now() + 1s);
}