Tests whether a file access error has occurred
#include <stdio.h> int ferror ( FILE *fp );
The ferror( ) functionoften implemented as a macrotests whether an error has been registered in reading or writing a given file.
ferror( )'s argument is a FILE pointer. One attribute of the file or stream referenced by this pointer is an error flag which indicates that an error has occurred during a read or write operation. The ferror( ) function or macro tests the error flag and returns a nonzero value if the flag is set. If not, ferror( ) returns 0.