Chapter 13 Quick Reference

Chapter 13 Quick Reference

To	Do this
Open a text file	Use the FileOpen function. For example: FileOpen(1, OpenFileDialog1.FileName, _ OpenMode.Input)
Get a line of input from a text file	Use the LineInput function. For example: Dim LineOfText As String LineOfText = LineInput(1)
Check for the end of a file	Use the EOF function. For example: Dim LineOfText, AllText As String Do Until EOF(1) LineOfText = LineInput(1) AllText = AllText & LineOfText & _ vbCrLf Loop
Close an open file	Use the FileClose function. For example: FileClose(1)
Display a text file by using LineInput	Use the LineInput function to copy text from an open file to a string variable, and then assign the string variable to a text box object. For example: Dim AllText, LineOfText As String Do Until EOF(1) 'read lines from file LineOfText = LineInput(1) AllText = AllText & LineOfText & _ vbCrLf Loop txtNote.Text = AllText 'display file
Display a text file by using the StreamReader class	Add the statement “Imports System.IO” to your form's declaration section, and then use StreamReader. For example, to display the file in a text box object named TextBox1: Dim StreamToDisplay As StreamReader StreamToDisplay = _ New StreamReader("c:\vb05sbs\chap13\text browser\badbills.txt") TextBox1.Text = StreamToDisplay.ReadToEnd StreamToDisplay.Close() TextBox1.Select(0, 0)
Display a text file by using the My object	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" ofd.ShowDialog() If ofd.FileName <> "" Then AllText = _ My.Computer.FileSystem.ReadAllText(ofd.FileName) txtNote.Text = AllText 'display file End If
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: OpenFileDialog1.ShowDialog()
Create a new text file	Use the FileOpen function. For example: FileOpen(1, SaveFileDialog1.FileName, _ OpenMode.Output)
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: SaveFileDialog1.ShowDialog()
Save text to a file	Use the Print or PrintLine function. For example: PrintLine(1, txtNote.Text)
Convert text characters to ASCII codes	Use the Asc function. For example: Dim Code As Short Code = Asc("A") 'Code equals 65
Convert ASCII codes to text characters	Use the Chr function. For example: Dim Letter As Char Letter = Chr(65) 'Letter equals "A"
Extract characters from the middle of a string	Use the Substring method or the Mid function. For example: Dim Cols, Middle As String Cols = "First Second Third" Middle = Cols.SubString(6, 6) 'Middle = "Second"