Visual Basic 2005 in a Nutshell, Third Edition

DirectCast Function | 249

The Language

Reference

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• Using

Volume for attributes returns the volume label for the drive specified by

pathname instead of a matching filename.

• In previous versions of Visual Basic, the Dir function was commonly used to

determine whether a particular file existed. Although it can still be used for this

purpose, the System.IO.File.Exists method is more straightforward. In Visual

Basic 2005, the My.Computer.FileSystem.FileExists method also checks for the

existence of a file.

• The

Dir function returns filenames in the order in which they appear in the file-

allocation table.

• The

Dir function saves its state between invocations. This means that the func-

tion cannot be called recursively. For example, if the function returns the name of

the directory, you cannot then call the

Dir function to iterate the files in that

directory and then return to the original directory.

• If you are calling the

Dir function to return the names of one or more files, you

must provide an explicit file specification. For instance, if you want to retrieve the

names of all files in the Windows directory, the function call:

fileMatch = Dir("C:\windows", FileAttribute.Normal)

fails. Instead, the Dir function must be called with pathname defined as follows:

fileMatch = Dir("C:\windows\*.*", ...