Microsoft Visual Basic 2010 Step by Step eBook

Chapter 13 Exploring Text Files and String Processing 315

The My namespace is truly a “speed dial” feature, fully explorable via the Microsoft

IntelliSense feature of the Code Editor. For example, to use a message box to display the

name of the current computer followed by the name of the current user in a program, you

can simply type:

MsgBox(My.User.Name)

This produces output similar to the following:

The My.Computer object can display many categories of information about your computer

and its files. For example, the following statement displays the current system time (the local

date and time) maintained by the computer:

MsgBox(My.Computer.Clock.LocalTime)

This produces output like this (your date and time will probably be different):

You can use the My.Computer.FileSystem object along with the ReadAllText method to open

a text file and display its contents within a text box object. Here’s the syntax you can use

if you have a text box object on your form named txtNote (as in the last sample program)

and you plan to use an open file dialog object named OpenFileDialog1 to get the name

of the text file from the user:

Dim AllText As String = ""

OpenFileDialog1.Filter = "Text files (*.txt)|*.txt"

If OpenFileDialog1.ShowDialog() = DialogResult.OK Then 'display Open dialog box

AllText = My.Computer.FileSystem.ReadAllText(OpenFileDialog1.FileName)

txtNote.Text = AllText 'display file

End If

The ReadAllText method copies the entire contents of the specified text file to a string

variable or object (in this case, a string variable named AllText), so in terms of performance

and coding time, ReadAllText is faster than reading the file one line at a time.