# ferror

## Purpose

Query MATLAB about errors in file input or output.

## Synopsis

    message = ferror(fid)
    message = ferror(fid,'clear')
    [message, errnum] = ferror(...)

## Description

`message = ferror(fid)` returns the error message `message`. `fid` is a file identifier associated with an open file. (See `fopen` for a complete description of `fid`.)

`message = ferror(fid,'clear')` clears the error indicator for the specified file.

`[message, errnum] = ferror(...)` returns the error status number `errnum` of the most recent file I/O operation associated with the specified file.

If the most recent I/O operation performed on the specified file was successful, `ferror` returns an `errnum` value of 0 and the value of `message` is empty.

A nonzero `errnum` indicates an error occurred in the most recent file I/O operation. Two ways that you can learn more about the nature of the error are

- The value of `message` is a string that may contain information about the nature of the error.
- If you have access to a C language reference manual, you can look at the error codes generated by file I/O operations provided by the C language library `stdio`.

  ## See Also

      fclose, fopen, fprintf, fread, fscanf, fseek, ftell, fwrite, sprintf,
      sscanf

  (c) Copyright 1994 by The MathWorks, Inc.