Appendix T : File-System Classes


A Visual Basic application can take three basic approaches to file system manipulation: Visual Basic methods, System.IO Framework classes, and the My.Computer.FileSystem namespace. This appendix summaries the properties, methods, and events provided by these approaches.

Visual Basic Methods

The following table summarizes the Visual Basic methods for working with files. They let a program create, open, read, write, and learn about files.

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Function

Purpose

EOF

Returns True if the file is at the end of file.

FileClose

Closes an open file.

FileGet

Reads data from a file opened in Random and Binary mode into a variable.

FileGetObject

Reads data as an object from a file opened in Random and Binary mode into a variable.

FileOpen

Opens a file for reading or writing. Parameters indicate the mode (Append, Binary, Input, Output, or Random), access type (Read, Write, or ReadWrite), and sharing (Shared, LockRead, LockWrite, or LockReadWrite).

FilePut

Writes data from a variable into a file opened for Random or Binary access.

FilePutObject

Writes an object from a variable into a file opened for Random or Binary access.

FreeFile

Returns a file number that is not currently associated with any file in this application. You should use FreeFile to get file numbers rather than using arbitrary numbers such as 1.

Input

Reads data written into a file by the Write method back into a variable.

InputString

Reads a specific number of characters from the file.

LineInput

Returns the next line of text from the file.

Loc

Returns the current position within the file.

LOF

Returns the file’s length in bytes.

Print

Prints values into the file. Multiple values separated by commas are aligned at tab boundaries.

PrintLine

Prints values followed by a new line into the file. Multiple values separated by commas are aligned at tab boundaries.

Seek

Moves to the indicated position within the file.

Write

Writes values into the file, delimited appropriately so that they can later be read by the Input method.

WriteLine

Writes values followed by a new line into the file, delimited appropriately so that they can later be read by the Input method.

The following table describes Visual Basic methods that manipulate directories and files. They let an application list, rename, move, copy, and delete files and directories.

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Method

Purpose

ChDir

Changes the application’s current working directory.

ChDrive

Changes the application’s current working drive.

CurDir

Returns the application’s current working directory.

Dir

Returns a file matching a directory path specification that may include wildcards, and matching certain file properties such as ReadOnly, Hidden, or Directory. The first call to Dir should include a path. Subsequent calls can omit the path to fetch the next matching file for the initial path. Dir returns file names without the path and returns Nothing when no more files match.

FileCopy

Copies a file to a new location.

FileDateTime

Returns the date and time when the file was created or last modified.

FileLen

Returns the length of a file in bytes.

GetAttr

Returns a value indicating the file’s attributes. The value is a combination of the values vbNormal, vbReadOjnly, vbHidden, vbSystem, vbDirectory, vbArchive, and vbAlias.

Kill

Permanently deletes a file.

MkDir

Creates a new directory.

Rename

Renames a directory or file.

RmDir

Deletes an empty directory.

SetAttr

Sets the file’s attributes The value is a combination of the values vbNormal, vbReadOjnly, vbHidden, vbSystem, vbDirectory, vbArchive, and vbAlias.




Visual Basic 2005 with  .NET 3.0 Programmer's Reference
Visual Basic 2005 with .NET 3.0 Programmer's Reference
ISBN: 470137053
EAN: N/A
Year: 2007
Pages: 417

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