ferror---test whether read/write error has occurred#include <stdio.h> int ferror(FILE *fp);Description
stdio functions maintain an error indicator with each file
pointer fp, to record whether any read or write errors have
occurred on the associated file or stream.
Use ferror to query this indicator.
See clearerr to reset the error indicator.
Returns
ferror returns 0 if no errors have occurred; it returns a
nonzero value otherwise.
Portability
ANSI C requires ferror.
No supporting OS subroutines are required.