__FB_64BIT__

如果编译目标平台是64位，编译时创建Define, 否则创建undefined.

#ifdef __FB_64BIT__
  '...instructions for 64bit OSes...
#else
  '...instructions for other OSes
#endif 

• 新的FreeBASIC
  
  

• __FB_LINUX__
  
• __FB_FREEBSD__
  
• __FB_OPENBSD__
  
• __FB_NETBSD__
  
• __FB_CYGWIN__
  
• __FB_DARWIN__
  
• __Fb_Pcos__
  
• 编译器选项：-target