My.Computer.FileSystem.ReadAllText Method

ReadAllText Method (My.Computer.Fil...

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Microsoft Visual Studio 2008/.NET Framework 3.5

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Visual Basic Language Reference

My.Computer.FileSystem.ReadAllText Method

Returns the contents of a text file as a String.

' Usage
Dim value As String = My.Computer.FileSystem.ReadAllText(file)
Dim value As String = My.Computer.FileSystem.ReadAllText(file ,encoding)
' Declaration
Public Function ReadAllText( _
   ByVal file As String _
) As String
' -or-
Public Function ReadAllText( _
   ByVal file As String, _
   ByVal encoding As System.Text.Encoding _
) As String

Parameters

file: String. Name and path of the file to read. Required.
encoding: System.Text..::.Encoding. Character encoding to use in reading the file. Required. Default is UTF-8.

Return Value

String containing the contents of the file.

Exceptions

The contents of the file may not be what is expected, and methods to read from the file may fail.

The following conditions may cause an exception:

The path is not valid for one of the following reasons: it is a zero-length string; it contains only white space; it contains invalid characters; or it is a device path (starts with \\.\) (ArgumentException).
The file name ends with a trailing slash (ArgumentException).
The path is not valid because it is Nothing (ArgumentNullException).
The file does not exist (FileNotFoundException).
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).
There is not enough memory to write the string to buffer (OutOfMemoryException).
The user lacks necessary permissions to view the path (SecurityException).

Remarks

The ReadAllText method of the My.Computer.FileSystem object allows you to read from a text file. The contents of the file are returned as a string.

The file encoding can be specified if the contents of the file are in an encoding such as ASCII or UTF-8. If you are reading from a file with extended characters, you need to specify the file encoding.

Do not make decisions about the contents of the file based on the name of the file. For example, the file Form1.vb may not be a Visual Basic source file. Verify all inputs before using the data in your application.

Tasks

The following table lists examples of tasks involving the My.Computer.FileSystem.ReadAllText method.

To	See
Read from a text file	How to: Read From Text Files in Visual Basic

Example

This example reads the contents of Test.txt into a string and then displays it in a message box.

Visual Basic

Dim reader As String
reader = My.Computer.FileSystem.ReadAllText("C:\test.txt")
MsgBox(reader)

This example reads the contents of the ASCII file Test.txt into a string and then displays it in a message box.

Visual Basic

Dim reader As String
reader = My.Computer.FileSystem.ReadAllText("C:\test.txt", _
   System.Text.Encoding.ASCII)
MsgBox(reader)

Requirements

Namespace: Microsoft.VisualBasic.MyServices

Class: FileSystemProxy (provides access to FileSystem)

Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)

Availability by Project Type

Project type	Available
Windows Application	Yes
Class Library	Yes
Console Application	Yes
Windows Control Library	Yes
Web Control Library	Yes
Windows Service	Yes
Web Site	Yes

Permissions

The following permission may be necessary:

Permission	Description
FileIOPermission	Controls the ability to access files and folders. Associated enumeration: Unrestricted.

For more information, see Code Access Security and Requesting Permissions.

Availability by Project Type

Tasks

Concepts

Reference

Other Resources