A common question in the Visual Basic forums on the Web is: "How do I parse a comma delimited file?".

For those using Visual Basic 2005, a good solution is the new TextFieldParser class.

The TextFieldParser class provides a way to parse structured text files. A TextFieldParser object can be used to read both delimited and fixed-width files.

The code example below show how to parse a comma delimited text file using a TextFieldParser object.

Code Example

Private Sub LoadCommaDelimetedTextFileIntoListBox(ByVal filePath As String)

        ' Declare a variable named theTextFieldParser of type TextFieldParser.

        Dim theTextFieldParser As TextFieldParser

        ' Call the My feature's OpenTextFieldParser method passing in a file path.

        ' Assign the resulting TxtFileParser object to theTextFieldParser variable.

        theTextFieldParser = My.Computer.FileSystem.OpenTextFieldParser(filePath)

        ' Set TextFieldParser object's TextFieldType property to Delimited.

        theTextFieldParser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited

        ' Configure delimiters to handle a comma delimited text file:

        ' Set TextFieldParser object's Delimiter's property to a string array

        ' containing one element with the value ",".

        theTextFieldParser.Delimiters = New String() {","}

        ' Declare a variable named currentRow of type string array.

        Dim currentRow() As String

        ' While the end of file has not been reached....

        While Not theTextFieldParser.EndOfData

            Try

                ' Read the fields on the current line

                ' and assign them to the currentRow array variable.

                currentRow = theTextFieldParser.ReadFields()

                ' Declare a variable named currentField of type String.

                Dim currentField As String

                ' Use the currentField variable to loop

                ' through fields in the currentRow.

                For Each currentField In currentRow

                    ' Add the the currentField (a string)

                    ' to the demoLstBox items.

                    Me.demoListBox.Items.Add(currentField)

                Next

            Catch malFormLineEx As Microsoft.VisualBasic.FileIO.MalformedLineException

                MessageBox.Show("Line " & malFormLineEx.Message & "is not valid and will be skipped.", "Malformed Line Exception")

            Catch ex As Exception

                MessageBox.Show(ex.Message & " exception has occurred.", "Exception")

            Finally

                ' If successful or if an exception is thrown,

                ' close the TextFieldParser.

                theTextFieldParser.Close()

            End Try

        End While

Click the link above to download Visual Basic source code in a Visual Studio 2005 solution which demonstrates how to use the TextFieldParser to parse a comma delimited text file and fill a ListBox with the result.

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