TextFieldParser.PeekChars Method (Int32)


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Reads the specified number of characters without advancing the cursor.

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

public string PeekChars(
	int numberOfChars


Type: System.Int32

Int32. Number of characters to read. Required.

Return Value

Type: System.String

A string that contains the specified number of characters read.

Exception Condition

numberOfChars is less than 0.

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.



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 "")
            currentRow = MyReader.ReadFields()
            For Each currentField As String In currentRow
                   "C://testfile.txt", currentField, True)
        Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
            MsgBox("Line " & ex.Message & " is invalid.  Skipping")
        End Try
    End While
End Using

.NET Framework
Available since 2.0
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