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Learn more about: How to: Read Text from Files with a StreamReader (Visual Basic)
How to: Read Text from Files with a StreamReader
07/20/2015
reading files [Visual Basic], text
text, reading from files
reading text from files [Visual Basic]
files [Visual Basic], reading
384033c6-18f9-4d59-9610-36371226558f

How to: Read Text from Files with a StreamReader (Visual Basic)

The My.Computer.FileSystem object provides methods to open a xref:System.IO.TextReader and a xref:System.IO.TextWriter. These methods, OpenTextFileWriter and OpenTextFileReader, are advanced methods that do not appear in IntelliSense unless you select the All tab.

To read a line from a file with a text reader

  • Use the OpenTextFileReader method to open the xref:System.IO.TextReader, specifying the file. This example opens the file named testfile.txt, reads a line from it, and displays the line in a message box.

    [!code-vbVbFileIORead#1]

Robust Programming

The file that is read must be a text file.

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

.NET Framework Security

To read from a file, your assembly requires a privilege level granted by the xref:System.Security.Permissions.FileIOPermission class. If you are running in a partial-trust context, the code might throw an exception due to insufficient privileges. For more information, see Code Access Security Basics. The user also needs access to the file. For more information, see ACL Technology Overview.

See also

  • xref:Microsoft.VisualBasic.FileIO.FileSystem
  • xref:System.Windows.Forms.OpenFileDialog
  • xref:Microsoft.VisualBasic.FileIO.FileSystem.OpenTextFileWriter%2A
  • xref:Microsoft.VisualBasic.FileIO.FileSystem.OpenTextFileReader%2A
  • SaveFileDialog Component
  • Reading from Files