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TextFieldParser.PeekChars Method

Reads the specified number of characters without advancing the cursor.

' Usage
Dim value As String = TextFieldParserObject.PeekChars(numberOfChars)
' Declaration
Public Function PeekChars( _
   ByVal numberOfChars As Integer _
) As String

numberOfChars

Int32. Number of characters to read. Required.

The following condition may cause an exception to be thrown:

The numberOfChars value must be less than the total number of characters in the line. If it is not, the string returned by PeekChars will be truncated to the length of the line.

Blank lines are ignored.

End-of-line characters are not returned.

The PeekChars method performs no parsing; an end-of- line character within a delimited field is interpreted as the actual end of the line.

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

To

See

Determine the format of a field before parsing it

How to: Read From Text Files with Multiple Formats in Visual Basic

This example uses PeekChars to find the end of the data and stop parsing the file at that point.

Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser("C:\ParserText.txt")
    MyReader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
    MyReader.Delimiters = New String() {","}
    MyReader.CommentTokens = New String() {"'"}
    Dim currentRow As String()
    While (MyReader.PeekChars(1) IsNot "")
        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

Namespace: Microsoft.VisualBasic.FileIO

Class: TextFieldParser

Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)

The following permissions are required:

Permission

Description

FileIOPermission

Controls the ability to access files and folders. Associated enumeration: Unrestricted.

SecurityPermission

Describes a set of security permissions applied to code. Associated enumeration: ControlEvidence.

For more information, see Code Access Security and Requesting Permissions.

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