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TextFieldParser.PeekChars Method

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
)

Parameters

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.

ExceptionCondition
ArgumentException

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.

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

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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