TextFieldParser.ReadFields Method
Reads all fields on the current line, returns them as an array of strings, and advances the cursor to the next line containing data.
' Usage
Dim value As String() = TextFieldParserObject.ReadFields()
' Declaration
Public Function ReadFields() As String()
Return Value
String ().
Exceptions
The following condition may cause an exception to be thrown:
- A field cannot be parsed using the specified format (MalformedLineException).
Remarks
In order to allow users to parse text files in multiple formats, the ReadFields method examines the values of TextFieldType, Delimiters, and FieldWidths, if they are specified, each time it is called. Users need to correctly configure the TextFieldType and FieldWidths or Delimiters properties, as appropriate. If TextFieldType is set to Delimited and Delimiters is not set, or if TextFieldType is set to FixedWidth and FieldWidths is not set, an exception is thrown.
If ReadFields encounters blank lines, they are skipped and the next non-blank line is returned.
Note
If the ReadFields method cannot parse the current line, it raises an exception and does not move to the next line. This enables your application to attempt to parse the line again.
Tasks
The following table lists examples of tasks involving the ReadFields method.
To |
See |
|---|---|
Read from a delimited file |
How to: Read From Comma-Delimited Text Files in Visual Basic |
Read from a fixed-width file |
Example
This example uses the ReadFields method to read from the file ParserText.txt and write the fields to Testfile.txt.
Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser("C:\ParserText.txt")
MyReader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
MyReader.Delimiters = New String() {","}
Dim currentRow As String()
While Not MyReader.EndOfData
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:
Permission |
Description |
|---|---|
Associated enumeration: Unrestricted. |
|
Associated enumeration: ControlEvidence. |
For more information, see Code Access Security and Requesting Permissions.
See Also
Tasks
How to: Read From Comma-Delimited Text Files in Visual Basic
How to: Read From Fixed-width Text Files in Visual Basic
How to: Read From Text Files with Multiple Formats in Visual Basic
Concepts
Parsing Text Files with the TextFieldParser Object
Reference
TextFieldParser.TextFieldType Property
TextFieldParser.FieldWidths Property