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TextFieldParser.PeekChars(Int32) Method

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Definition

Namespace:
Microsoft.VisualBasic.FileIO
Assembly:
Microsoft.VisualBasic.Core.dll
Assembly:
Microsoft.VisualBasic.dll
Source:
TextFieldParser.vb
Source:
TextFieldParser.vb
Source:
TextFieldParser.vb

Reads the specified number of characters without advancing the cursor.

public:
 System::String ^ PeekChars(int numberOfChars);
public string? PeekChars (int numberOfChars);
public string PeekChars (int numberOfChars);
member this.PeekChars : int -> string
Public Function PeekChars (numberOfChars As Integer) As String

Parameters

numberOfChars
Int32

The number of characters to read. Required.

Returns

String

A string that contains the specified number of characters read.

Exceptions

ArgumentException

numberOfChars is less than 0.

Examples

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

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.

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

Applies to

See also