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 |
Example
This example reads the contents of Test.txt into a string and then displays it in a message box.
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.
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 |
|---|---|
Controls the ability to access files and folders. Associated enumeration: Unrestricted. |
For more information, see Code Access Security and Requesting Permissions.
See Also
Tasks
How to: Read Text from Files with a StreamReader (Visual Basic)
Troubleshooting: Reading from and Writing to Text Files
Walkthrough: Manipulating Files and Directories in Visual Basic