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How to: Write to Binary Files in Visual Basic 

The My.Computer.FileSystem.WriteAllBytes Method writes data to a binary file. If the append parameter is True, it will append the data to the file; otherwise data in the file is overwritten.

If the specified path excluding the file name is not valid, a DirectoryNotFoundException exception will be thrown. If the path is valid but the file does not exist, the file will be created.

To write to a binary file

  • Use the WriteAllBytes method, supplying the file path and name and the bytes to be written. This example appends the data array CustomerData to the file named CollectedData.dat.

    My.Computer.FileSystem.WriteAllBytes _
    ("C:\MyDocuments\CustomerData", CustomerData, True)

Robust Programming

The following conditions may create an exception:

  • The path is not valid for one of the following reasons: it is a zero-length string; it contains only white space; or it contains invalid characters. (ArgumentException).

  • The path is not valid because it is Nothing (ArgumentNullException).

  • File points to a path that does not exist (FileNotFoundException or DirectoryNotFoundException).

  • The file is in use by another process, or an I/O error occurs (IOException).

  • The path exceeds the system-defined maximum length (PathTooLongException).

  • A file or directory name in the path contains a colon (:) or is in an invalid format (NotSupportedException).

  • The user lacks necessary permissions to view the path (SecurityException).

See Also