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FileUpload.FileBytes Property

Gets an array of the bytes in a file that is specified by using a FileUpload control.

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

[BindableAttribute(true)]
[BrowsableAttribute(false)]
public byte[] FileBytes { get; }

Property Value

Type: System.Byte[]
A Byte array that contains the contents of the specified file.

ExceptionCondition
HttpException

The entire file was not read.

The FileUpload control does not automatically read the file from the client. You must explicitly provide a control or mechanism to allow the user to submit the specified file. For example, you can provide a button that the user can click to upload the file. The code that you write to save the specified file could call the FileBytes property, which returns the contents of the file.

Before calling the FileBytes property, you should use the HasFile property to verify that the FileUpload control contains a file to upload. If the HasFile returns true, call the FileBytes property. If it returns false, display a message to the user indicating that the control does not contain a file. If you do not provide error-handling code to verify that a file exists, an attempt to save a nonexistent file throws an HttpException exception.

The following example demonstrates how to create a FileUpload control. When the user clicks the Upload file button, the contents of the file are displayed as bytes in a text box on the page. This example uses the FileBytes property to upload the entire file.

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>FileUpload.FileContent Property Example</title>
<script runat="server">

        private void DisplayFileContents(HttpPostedFile file) 
        {            
            int fileLen;
            string displayString = "";

            // Get the length of the file.
            fileLen = FileUpload1.PostedFile.ContentLength;

            // Display the length of the file in a label.
            LengthLabel.Text = "The length of the file is "
                               + fileLen.ToString() + " bytes.";

            // Create a byte array to hold the contents of the file.
            byte[] input = new byte[fileLen - 1];
            input = FileUpload1.FileBytes;

            // Copy the byte array to a string.
            for (int loop1 = 0; loop1 < fileLen; loop1++) {
                displayString = displayString + input[loop1].ToString();
            }

            // Display the contents of the file in a 
            // textbox on the page.
            ContentsLabel.Text = "The contents of the file as bytes:";

            TextBox ContentsTextBox = new TextBox();
            ContentsTextBox.TextMode = TextBoxMode.MultiLine;
            ContentsTextBox.Height = Unit.Pixel(300);
            ContentsTextBox.Width = Unit.Pixel(400);
            ContentsTextBox.Text = displayString;

            // Add the textbox to the Controls collection
            // of the Placeholder control.
            PlaceHolder1.Controls.Add(ContentsTextBox);

        }

    protected void  UploadButton_Click(object sender, EventArgs e)
    {
            // Specify the path on the server to
            // save the uploaded file to.
            string savePath = @"c:\temp\uploads\";

            // Before attempting to perform operations
            // on the the file, verify that the FileUpload 
            // control contains a file.
            if (FileUpload1.HasFile) {

                // Append the name of the file to upload to the path.
                savePath += FileUpload1.FileName;

                // Call the SaveAs method to save the 
                // uploaded file to the specified path.
                // This example does not perform all
                // the necessary error checking.               
                // If a file with the same name
                // already exists in the specified path,  
                // the uploaded file overwrites it.
                FileUpload1.SaveAs(savePath);

                // Notify the user that the file was uploaded successfully.
                UploadStatusLabel.Text = "Your file was uploaded successfully.";

                // Call a helper routine to display the contents
                // of the file to upload.
                DisplayFileContents(FileUpload1.PostedFile);
            }
            else
            {
                // Notify the user that a file was not uploaded.
                UploadStatusLabel.Text = "You did not specify a file to upload.";
            }
    }
</script>

</head>
<body>

    <h3>FileUpload.FileContent Property Example</h3>

    <form id="Form1" runat="server">

        <h4>Select a file to upload:</h4>

        <asp:FileUpload id="FileUpload1"
           runat="server">
        </asp:FileUpload>

        <br /><br />

        <asp:Button id="UploadButton" 
            Text="Upload file"
            OnClick="UploadButton_Click"
            runat="server">
        </asp:Button>

        <br /><br />

        <asp:Label id="UploadStatusLabel"
           runat="server">
        </asp:Label>  

        <hr />

        <asp:Label id="LengthLabel"
           runat="server">
        </asp:Label>  

        <br /><br />

        <asp:Label id="ContentsLabel"
           runat="server">
        </asp:Label>  

        <br /><br />

        <asp:PlaceHolder id="PlaceHolder1"
            runat="server">
        </asp:PlaceHolder>         

    </form>

</body>
</html>

.NET Framework

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

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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