c语言FILE结构体的定义：
<stdin.h>
/* Define outside of namespace so the C++ is happy. */ struct _IO_FILE; __BEGIN_NAMESPACE_STD /* The opaque type of streams. This is the definition used elsewhere. */ typedef struct _IO_FILE FILE; __END_NAMESPACE_STD #if defined __USE_LARGEFILE64 || defined __USE_SVID || defined __USE_POSIX \ || defined __USE_BSD || defined __USE_ISOC99 || defined __USE_XOPEN \ || defined __USE_POSIX2 __USING_NAMESPACE_STD(FILE) #endif # define __FILE_defined 1 #endif /* FILE not defined. */ #undef __need_FILE #if !defined ____FILE_defined && defined __need___FILE /* The opaque type of streams. This is the definition used elsewhere. */ typedef struct _IO_FILE __FILE;
<libio.h>
struct _IO_FILE { int _flags; /* High-order word is _IO_MAGIC; rest is flags. */ #define _IO_file_flags _flags /* The following pointers correspond to the C++ streambuf protocol. */ /* Note: Tk uses the _IO_read_ptr and _IO_read_end fields directly. */ char* _IO_read_ptr; /* Current read pointer */ char* _IO_read_end; /* End of get area. */ char* _IO_read_base; /* Start of putback+get area. */ char* _IO_write_base; /* Start of put area. */ char* _IO_write_ptr; /* Current put pointer. */ char* _IO_write_end; /* End of put area. */ char* _IO_buf_base; /* Start of reserve area. */ char* _IO_buf_end; /* End of reserve area. */ /* The following fields are used to support backing up and undo. */ char *_IO_save_base; /* Pointer to start of non-current get area. */ char *_IO_backup_base; /* Pointer to first valid character of backup area */ char *_IO_save_end; /* Pointer to end of non-current get area. */ struct _IO_marker *_markers; struct _IO_FILE *_chain; int _fileno; #if 0 int _blksize; #else int _flags2; #endif _IO_off_t _old_offset; /* This used to be _offset but it's too small. */ #define __HAVE_COLUMN /* temporary */ /* 1+column number of pbase(); 0 is unknown. */ unsigned short _cur_column; signed char _vtable_offset; char _shortbuf[1]; /* char* _save_gptr; char* _save_egptr; */ _IO_lock_t *_lock; #ifdef _IO_USE_OLD_IO_FILE };