unsigned int sleep(unsigned int seconds);

   DESCRIPTION
          sleep()  makes  the  calling thread sleep until
          seconds seconds have elapsed or a signal arrives which is not ignored.

unsigned int time_to_sleep = 10; // sleep 10 seconds
 while(time_to_sleep)
     time_to_sleep = sleep(time_to_sleep);

while( true )
{
    // your stuff
    sleep( 10 ); // sleeping for 10 seconds
};

#include <unistd.h>
sleep(10); // 10 seconds

#include <windows.h>
Sleep(10000); // 10 seconds (10000 milliseconds)