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How to: Read From Text Files in Visual Basic

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The ReadAllText method of the My.Computer.FileSystem object allows you to read from a text file. The file encoding can be specified if the contents of the file use an encoding such as ASCII or UTF-8.

If you are reading from a file with extended characters, you will need to specify the file encoding.

Note

To read a file a single line of text at a time, use the OpenTextFileReader method of the My.Computer.FileSystem object. The OpenTextFileReader method returns a StreamReader object. You can use the ReadLine method of the StreamReader object to read a file one line at a time. You can test for the end of the file using the EndOfStream method of the StreamReader object.

To read from a text file

Use the ReadAllText method of the My.Computer.FileSystem object to read the contents of a text file into a string, supplying the path. The following example reads the contents of test.txt into a string and then displays it in a message box.

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

To read from a text file that is encoded

Use the ReadAllText method of the My.Computer.FileSystem object to read the contents of a text file into a string, supplying the path and file encoding type. The following example reads the contents of the UTF32 file test.txt into a string and then displays it in a message box.

Dim fileReader As String
fileReader = My.Computer.FileSystem.ReadAllText("C:\test.txt",
   System.Text.Encoding.UTF32)
MsgBox(fileReader)

Robust Programming

The following conditions may cause an exception:

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.

See also