Detect Mac OS X version

#include <Carbon/Carbon.h>

int main(int argc, char* argv[])
{
    DialogRef alert;
    DialogItemIndex outHit;
    long versMaj, versMin, versBugFix;
    CFStringRef str;
    
    Gestalt(gestaltSystemVersionMajor, &versMaj);
    Gestalt(gestaltSystemVersionMinor, &versMin);
    Gestalt(gestaltSystemVersionBugFix, &versBugFix);
    str = CFStringCreateWithFormat(NULL, NULL, 
               CFSTR("Mac OS X ver.%d.%d.%d"), 
               versMaj, versMin, versBugFix);
        CreateStandardAlert(kAlertDefaultOKText,  
               CFSTR("Hello"), str, NULL, &alert);
       RunStandardAlert(alert, NULL, &outHit);    
    CFRelease(str);
    
    return 0;
}