HttpResponse.WriteFile Method (String, Int64, Int64)


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Writes the specified file directly to an HTTP response output stream.

Namespace:   System.Web
Assembly:  System.Web (in System.Web.dll)

Public Sub WriteFile (
	filename As String,
	offset As Long,
	size As Long


Type: System.String

The name of the file to write to the HTTP output stream.

Type: System.Int64

The byte position in the file where writing will start.

Type: System.Int64

The number of bytes to write to the output stream.

Exception Condition

offset is less than 0.

- or -

size is greater than the file size minus offset.


The filename parameter is null.

When this method is used with large files, calling the method might throw an exception. The size of the file that can be used with this method depends on the hardware configuration of the Web server. For more information, see article 812406, "PRB: Response.WriteFile Cannot Download a Large File" on the Microsoft Knowledge Base Web site.

The following example writes all the contents of a text file named Login.txt (which might contain literal text and HTML input controls) directly to the output stream.

Dim FileName As String
 Dim MyFileInfo As FileInfo
 Dim StartPos, FileSize As Long

 FileName = "c:\\temp\\login.txt"
 MyFileInfo = New FileInfo(FileName)
 FileSize = MyFileInfo.Length 

 Response.Write("Please Login: <br>")
 Response.WriteFile(FileName, StartPos, FileSize)

.NET Framework
Available since 1.1
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