C Language File Structure body

In the stdio.h header file of the C language, a struct file is defined for the operation of the document. In this way, we return a file pointer (a pointer to the file structure body) through fopen to file operations.

#ifndef _file_defined
struct _IOBUF {

char *_ptr;//File input next position
int _cnt;//The relative position of the current buffer
Char *_b Ase　　　　Refers to the base position (that is, the beginning of the file)
int _flag;//File flag
int _file;//file descriptor
int _charbuf;//check buffer condition, not read
if no buffer int _bufsiz; Buffer size
char *_tmpfname;//temporary file name

        };
typedef struct _IOBUF FILE;
#define _file_defined
#endif