ferror、feof、clearerr、fileno

ferror, feof, clearerr, fileno - check and reset stream status

#include <stdio.h>

int ferror(FILE *stream);  //true if it's error
int feof(FILE *stream);    //true if it's eof
//Both Return: nonzero(true) if true, 0(false) if false
void clearerr(FILE *stream); //clear both flags
int fileno(FILE *stream);

在FILE object中有两个标志位（flags）

• An error flag
• An end-of-file flag

clearerr能清除所有标志位

fileno() examines the argument stream and returns its integer descriptor.(检测stream流，并且返回整数描述符)