Microsoft Visual Basic 2010 Step by Step eBook

Chapter 13 Exploring Text Files and String Processing 345

in your study of Visual Basic programming skills and in your use of the Visual Studio IDE. Take

a short break, and I’ll see you again in Part III, “Designing the User Interface”!

Chapter 13 Quick Reference

To Do This

Display an Open

dialog box

Add an OpenFileDialog control to your form, and then use the ShowDialog

method of the open file dialog object. For example:

If OpenFileDialog1.ShowDialog() = DialogResult.OK Then

Read a text file

by using the My

namespace

Use the My.Computer.FileSystem object and the ReadAllText method.

For example (assuming that you are also using an open file dialog object

named ofd and a text box object named txtNote):

Dim AllText As String = ""

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

If ofd.ShowDialog() = DialogResult.OK Then

AllText = _

My.Computer.FileSystem.ReadAllText(ofd.FileName)

txtNote.Text = AllText 'display file

End If

Read a text file

by using the

StreamReader class

Add the statement Imports System.IO to your form’s declaration section,

and then use StreamReader. Use the ReadToEnd method to read the entire

file. When finished, call the Close method. For example, to display the file in

a text box object named TextBox1:

Dim StreamToDisplay As StreamReader

StreamToDisplay = New StreamReader( _

"c:\vb10sbs\chap13\text browser\badbills.txt")

TextBox1.Text = StreamToDisplay.ReadToEnd

StreamToDisplay.Close()

Read a text file line

by line

Use StreamReader and the ReadLine method. Use the OpenTextFileReader

method in the My namespace to open a StreamReader. To check for the

end of the file, use the EndOfStream property:

Dim AllText As String = "", LineOfText As String = ""

Dim StreamToDisplay As StreamReader

StreamToDisplay = My.Computer.FileSystem.OpenTextFileReader( _

"C:\vb10sbs\chap13\text browser\badbills.txt")

Do Until StreamToDisplay.EndOfStream 'read lines from file

LineOfText = StreamToDisplay.ReadLine()

AllText = AllText & LineOfText & vbCrLf

Loop

TextBox1.Text = AllText 'display file

StreamToDisplay.Close()

Display a Save As

dialog box

Add a SaveFileDialog control to your form, and then use the ShowDialog

method of the save file dialog object. For example:

If SaveFileDialog1.ShowDialog() = DialogResult.OK Then