TextFieldParser.ReadFields Method ()

 

Reads all fields on the current line, returns them as an array of strings, and advances the cursor to the next line containing data.

Namespace:   Microsoft.VisualBasic.FileIO
Assembly:  Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)

public string[] ReadFields()

Return Value

Type: System.String[]

An array of strings that contains field values for the current line.

Exception Condition
MalformedLineException

A field cannot be parsed by using the specified format.

In order to allow users to parse text files in multiple formats, the ReadFields method examines the values of TextFieldType, Delimiters, and FieldWidths, if they are specified, each time it is called. Users need to correctly configure the TextFieldType and FieldWidths or Delimiters properties, as appropriate. If TextFieldType is set to Delimited, and Delimiters is not set, or if TextFieldType is set to FixedWidth and FieldWidths, an exception is thrown.

If ReadFields encounters blank lines, they are skipped and the next non-blank line is returned.

If the ReadFields method cannot parse the current line, it raises an exception and does not move to the next line. This enables your application to attempt to parse the line again.

The following table lists examples of tasks involving the ReadFields method.

To

See

Read from a delimited file

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

Read from a fixed-width file

How to: Read From Fixed-width Text Files in Visual Basic

This example uses the ReadFields method to read from the comma-delimited file ParserText.txt. The example writes the fields to Testfile.txt.

Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser("C:\ParserText.txt")
    MyReader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
    MyReader.Delimiters = New String() {","}
    Dim currentRow As String()
    While Not MyReader.EndOfData
        Try
            currentRow = MyReader.ReadFields()
            For Each currentField As String In currentRow
                My.Computer.FileSystem.WriteAllText(
                    "C://testfile.txt", currentField, True)
            Next
        Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
            MsgBox("Line " & ex.Message & " is invalid.  Skipping")
        End Try
    End While
End Using

FileIOPermission

Associated enumeration: Unrestricted.

SecurityPermission

Associated enumeration: ControlEvidence.

.NET Framework
Available since 2.0
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