File Processing

 Files that can be opened are files with the extensions .txt, ini, log or inf.  These files have no embedded formatting or other unrecognizable characters.

 Syntax:

FileOpen(filenumber, pathname, mode)

Filenumber is 1 through 255, you use this number when you write to the file and when you close

Pathname is a valid Windows path, including the filename and extension

Mode is a keyword indicating how to use the file. Input means data input to the current VB application.

 Example:

 fileOpen(1, file.txt, input)

 Example using the OpenFileDialog window

 fileOpen(1, OpenFileDialog1.FileName, OpenMode.Input)

FileOpen – opens the file

LineInput – reads one line from the input file

EOF – a check for the end of file marker

FileClose – closes the text file

Examples using the open dialog window:

open the file

FileOpen(1,SaveFileDialog1.FileName, OpenMode.Output)

write a line to the file

Printline(1,txtNote.Text)

Close the file

FileClose(1)

Uses a menu to collect the Opens File command.  Uses the OpenFileDialog to allow the user to select the file.  Makes use of Try..Catch to trap file errors. Has a comprehensive set of Reads the file and displays it in a textbox. Just a really nice little application.

Private Sub OpenToolStripMenuItem_Click _

(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles OpenToolStripMenuItem.Click

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

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

      OpenFileDialog1.ShowDialog() 'display Open dialog box

      If OpenFileDialog1.FileName <> "" Then

            Try 'open file and trap any errors using handler

            FileOpen(1, OpenFileDialog1.FileName, OpenMode.Input)

            Do Until EOF(1) 'read lines from file

                  LineOfText = LineInput(1)

                  'add each line to the AllText variable

                  AllText = AllText & LineOfText & vbCrLf

            Loop

            lblNote.Text = OpenFileDialog1.FileName  'update label

            txtNote.Text = AllText 'display file

            txtNote.Enabled = True 'allow text cursor

            CloseToolStripMenuItem.Enabled = True 

'enable Close command

            OpenToolStripMenuItem.Enabled = False 

'disable Open command

            Catch

            MsgBox("Error opening file.")

            Finally

            FileClose(1) 'close file

            End Try

      End If

End Sub