How to: Read From Comma-Delimited Text Files in Visual Basic

How to: Read From Comma-Delimited T...

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

Visual Basic Application Development

How to: Read From Comma-Delimited Text Files in Visual Basic

The TextFieldParser object provides a way to easily and efficiently parse structured text files, such as logs. The TextFieldType property defines whether it is a delimited file or one with fixed-width fields of text.

To parse a comma delimited text file

Create a new TextFieldParser. The following code creates the TextFieldParser named MyReader and opens the file test.txt.
Visual Basic
```
Using MyReader As New _
Microsoft.VisualBasic.FileIO.TextFieldParser _
("C:\TestFolder\test.txt")
```
Define the TextField type and delimiter. The following code defines the TextFieldType property as Delimited and the delimiter as ",".
Visual Basic
```
MyReader.TextFieldType = FileIO.FieldType.Delimited
MyReader.SetDelimiters(",")
```

Loop through the fields in the file. If any lines are corrupt, report an error and continue parsing. The following code loops through the file, displaying each field in turn and reporting any fields that are formatted incorrectly.

Visual Basic

Dim currentRow As String()
   While Not MyReader.EndOfData
      Try
         currentRow = MyReader.ReadFields()
         Dim currentField As String
         For Each currentField In currentRow
            MsgBox(currentField)
         Next
         Catch ex As _
         Microsoft.VisualBasic.FileIO.MalformedLineException
         MsgBox("Line " & ex.Message & _
         "is not valid and will be skipped.")
     End Try

Close the While and Using blocks with End While and End Using.
Visual Basic
```
   End While
End Using
```

Example

This example reads from the file test.txt.

Visual Basic

Using MyReader As New _
Microsoft.VisualBasic.FileIO.TextFieldParser("C:\testfile.txt")
   MyReader.TextFieldType = FileIO.FieldType.Delimited
   MyReader.SetDelimiters(",")
   Dim currentRow As String()
   While Not MyReader.EndOfData
      Try
         currentRow = MyReader.ReadFields()
         Dim currentField As String
         For Each currentField In currentRow
            MsgBox(currentField)
         Next
      Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
      MsgBox("Line " & ex.Message & _
      "is not valid and will be skipped.")
      End Try
   End While
End Using

Robust Programming

The following conditions may cause an exception:

A row cannot be parsed using the specified format (MalformedLineException). The exception message specifies the line causing the exception, while the TextFieldParser.ErrorLine Property is assigned the text contained in the line.
The specified file does not exist (FileNotFoundException).
A partial-trust situation in which the user does not have sufficient permissions to access the file. (SecurityException).
The path is too long (PathTooLongException).
The user does not have sufficient permissions to access the file (UnauthorizedAccessException).

To parse a comma delimited text file

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