Returns a nonzero integer if an error occurred while reading or
    writing a file.
    Format
      #include  <stdio.h>
      int ferror  (FILE *file_ptr);
1 – Argument
 file_ptr
    A file pointer.
2 – Description
    A call to ferror continues to return a nonzero integer until the
    file is closed or until clearerr is called.
3 – Return Values
    0                  Indicates success.
    nonzero integer    Indicates that an error has occurred.