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

Parameters

• numberOfChars
  Int32. Number of characters to read. Required.

Return Value

String.

Exceptions

The following condition may cause an exception to be thrown:

• numberOfChars is less than 0 (ArgumentException).

Remarks

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.

Tasks

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

Example

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

Requirements

Namespace: Microsoft.VisualBasic.FileIO

Class: TextFieldParser

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

Permissions

The following permissions are required:

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

See Also

Reference

TextFieldParser Object
PeekChars

Concepts

Parsing Text Files with the TextFieldParser Object

Other Resources

Reading from Files in Visual Basic