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StreamReader.Null Field

A StreamReader around an empty stream.

[Visual Basic]
Public Shared ReadOnly Null As StreamReader
[C#]
public static readonly StreamReader Null;
[C++]
public: static StreamReader* Null;
[JScript]
public static var Null : StreamReader;

Remarks

When read methods are invoked on StreamReader.Null, zero is always returned. When ReadLine is invoked on StreamReader.Null, a null reference (Nothing in Visual Basic) is returned.

For an example of using this field, see the Example section below. The following table lists examples of other typical or related I/O tasks.

To do this... See the example in this topic...
Create a text file. Writing Text to a File
Write to a text file. Writing Text to a File
Read from a text file. Reading Text from a File
Append text to a file. Opening and Appending to a Log File

File.AppendText

FileInfo.AppendText

Get the size of a file. FileInfo.Length
Get the attributes of a file. File.GetAttributes
Set the attributes of a file. File.SetAttributes
Determine if a file exists. File.Exists
Read from a binary file. Reading and Writing to a Newly Created Data File
Write to a binary file. Reading and Writing to a Newly Created Data File

Example

[Visual Basic, C#, C++] The following example demonstrates the Null field.

[Visual Basic] 
Dim SNull As Stream
SNull = File.OpenRead("C:\Temp\Test.txt")
Dim SrNull As StreamReader = New StreamReader(SNull, _
    System.Text.Encoding.ASCII)
If (SrNull.Equals(StreamReader.Null) <> True) Then
    SrNull.BaseStream.Seek(0, SeekOrigin.Begin)
    Console.WriteLine(SrNull.ReadToEnd())
End If
SrNull.Close()

[C#] 
StreamReader srNull = new StreamReader(
    (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
    System.Text.Encoding.ASCII);
if(!srNull.Equals(StreamReader.Null)) 
{
    srNull.BaseStream.Seek(0, SeekOrigin.Begin);
    Console.WriteLine(srNull.ReadToEnd());
}
srNull.Close();

[C++] 
StreamReader *srNull = new StreamReader(
    File::OpenRead("C:\\Temp\\Test.txt"),
    System::Text::Encoding::ASCII);
if(!srNull->Equals(StreamReader::Null)) {
    srNull->BaseStream->Seek(0, SeekOrigin::Begin);
    Console::WriteLine(srNull->ReadToEnd());
}
srNull->Close();

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

See Also

StreamReader Class | StreamReader Members | System.IO Namespace | Working with I/O | Reading Text from a File | Writing Text to a File

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