리눅스 / 맥오에스에서 CPU 갯수 얻기

#include <stdio.h>
#ifdef __linux__
#include <sys/sysinfo.h>
#else
#ifdef __APPLE__
#include <sys/param.h>
#include <sys/sysctl.h>
#else
#error "Only Linux or OSX is supported!"
#endif /* __APPLE__ */
#endif /* __linux__ */
 
static int
get_cpu_nr (void)
{
#ifdef __linux__
  return get_nprocs ();
#endif
#ifdef __APPLE__
  int i = 0;
  size_t s = sizeof (i);
  if (sysctlbyname ("hw.ncpu", &i, &s, NULL, 0))
    return 1;
  return i;
#endif
}
 
int
main (int argc, char **argv)
{
  printf ("cpu_nr:%d\n", get_cpu_nr ());
 
  return 0;
}