XmlTextReader.ReadBase64(Byte[], Int32, Int32) Method

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlTextReader.cs

Decodes Base64 and returns the decoded binary bytes.

public:
 int ReadBase64(cli::array <System::Byte> ^ array, int offset, int len);

public int ReadBase64 (byte[] array, int offset, int len);

member this.ReadBase64 : byte[] * int * int -> int

Public Function ReadBase64 (array As Byte(), offset As Integer, len As Integer) As Integer

Parameters

array

Byte[]

The array of characters that serves as the buffer to which the text contents are written.

offset

Int32

The zero-based index into the array specifying where the method can begin to write to the buffer.

len

Int32

The number of bytes to write into the buffer.

Returns

Int32

The number of bytes written to the buffer.

Exceptions

XmlException

The Base64 sequence is not valid.

ArgumentNullException

The value of array is null.

ArgumentOutOfRangeException

offset < 0, or len < 0, or len > array.Length- offset.

Examples

The following example reads a file containing Base64 and BinHex data.

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ reader = nullptr;
   String^ filename = "binary.xml";
   try
   {
      reader = gcnew XmlTextReader( filename );
      reader->WhitespaceHandling = WhitespaceHandling::None;
      
      // Read the file. Stop at the Base64 element.
      while ( reader->Read() )
      {
         if ( "Base64" == reader->Name )
                  break;
      }
      
      // Read the Base64 data. Write the decoded 
      // bytes to the console.
      Console::WriteLine( "Reading Base64... " );
      int base64len = 0;
      array<Byte>^base64 = gcnew array<Byte>(1000);
      do
      {
         base64len = reader->ReadBase64( base64, 0, 50 );
         for ( int i = 0; i < base64len; i++ )
            Console::Write( base64[ i ] );
      }
      while ( reader->Name->Equals( "Base64" ) );
      
      // Read the BinHex data. Write the decoded 
      // bytes to the console.
      Console::WriteLine( "\r\nReading BinHex..." );
      int binhexlen = 0;
      array<Byte>^binhex = gcnew array<Byte>(1000);
      do
      {
         binhexlen = reader->ReadBinHex( binhex, 0, 50 );
         for ( int i = 0; i < binhexlen; i++ )
            Console::Write( binhex[ i ] );
      }
      while ( reader->Name->Equals( "BinHex" ) );
   }
   finally
   {
      Console::WriteLine();
      Console::WriteLine( "Processing of the file {0} complete.", filename );
      if ( reader != nullptr )
            reader->Close();
   }

}

using System;
using System.IO;
using System.Xml;

public class Sample {

  private const string filename = "binary.xml";

  public static void Main() {

     XmlTextReader reader = null;

     try {

        reader = new XmlTextReader(filename);
        reader.WhitespaceHandling = WhitespaceHandling.None;

        // Read the file. Stop at the Base64 element.
        while (reader.Read()) {
           if ("Base64" == reader.Name) break;
        }
            
        // Read the Base64 data. Write the decoded
        // bytes to the console.
        Console.WriteLine("Reading Base64... ");
        int base64len = 0;
        byte[] base64 = new byte[1000];
        do {
           base64len = reader.ReadBase64(base64, 0, 50);
           for (int i=0; i < base64len; i++) Console.Write(base64[i]);
        } while (reader.Name == "Base64");
    
        // Read the BinHex data. Write the decoded
        // bytes to the console.
        Console.WriteLine("\r\nReading BinHex...");
        int binhexlen = 0;
        byte[] binhex = new byte[1000];
        do {
           binhexlen = reader.ReadBinHex(binhex, 0, 50);
           for (int i=0; i < binhexlen; i++) Console.Write(binhex[i]);
        }  while (reader.Name == "BinHex");
     }

     finally {
        Console.WriteLine();
        Console.WriteLine("Processing of the file {0} complete.", filename);
        if (reader != null)
          reader.Close();
     }
  }
}

Option Explicit
Option Strict

Imports System.IO
Imports System.Xml

Public Class Sample
   Private Const filename As String = "binary.xml"
   
   
   Public Shared Sub Main()
      Dim reader As XmlTextReader = Nothing
      Dim i As Integer

      Try
         reader = New XmlTextReader(filename)
         reader.WhitespaceHandling = WhitespaceHandling.None         

         ' Read the file. Stop at the Base64 element.         
         While reader.Read()
            If "Base64" = reader.Name Then
               Exit While
            End If
         End While 

         ' Read the Base64 data. Write the decoded 
         ' bytes to the console.
         Console.WriteLine("Reading base64... ")
         Dim base64len As Integer = 0
         Dim base64(1000) As Byte
         Do
            base64len = reader.ReadBase64(base64, 0, 50)
            For i = 0 To base64len - 1
               Console.Write(base64(i))
            Next i
         Loop While (reader.Name = "Base64")

         ' Read the BinHex data. Write the decoded 
         ' bytes to the console.
         Console.WriteLine(ControlChars.CrLf & "Reading binhex....")
         Dim binhexlen As Integer = 0
         Dim binhex(1000) As Byte
         binhexlen = reader.ReadBinHex(binhex, 0, 50)
         Do
            binhexlen = reader.ReadBinHex(binhex, 0, 50)
            For i = 0 To binhexlen - 1
               Console.Write(binhex(i))
            Next i
         Loop While (reader.Name = "BinHex") 
      
      Finally
         Console.WriteLine()
         Console.WriteLine("Processing of the file {0} complete.", filename)
         If Not (reader Is Nothing) Then
            reader.Close()
         End If
      End Try
   End Sub
End Class

The sample uses the file binary.xml

<data>
<!-- sample data for base64 and binhex -->
<Base64>AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS
4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFi
Y2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6PkJGSk5SVlp
eYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKztLW2t7i5uru8vb6/wMHCw8TFxsfIycrL
zM3Oz9DR0tPU1dbX2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w
==</Base64>
<BinHex>000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E
1F202122232425262728292A2B2C2D2E2F303132333435363738393A3B3C3D3E3F4041
42434445464748494A4B4C4D4E4F505152535455565758595A5B5C5D5E5F6061626364
65666768696A6B6C6D6E6F707172737475767778797A7B7C7D7E7F8081828384858687
88898A8B8C8D8E8F909192939495969798999A9B9C9D9E9FA0A1A2A3A4A5A6A7A8A9AA
ABACADAEAFB0B1B2B3B4B5B6B7B8B9BABBBCBDBEBFC0C1C2C3C4C5C6C7C8C9CACBCCCD
CECFD0D1D2D3D4D5D6D7D8D9DADBDCDDDEDFE0E1E2E3E4E5E6E7E8E9EAEBECEDEEEFF0
F1F2F3F4F5F6F7F8F9FAFBFCFDFEFF</BinHex>
</data>

Remarks

Note

Starting with the .NET Framework 2.0, we recommend that you create XmlReader instances by using the XmlReader.Create method to take advantage of new functionality.

Like ReadChars, this method can be called successively to read large streams of embedded text. It decodes Base64 content and returns the decoded binary bytes (for example, an inline Base64 encoded GIF image) into the buffer. See RFC 1521. (You can obtain RFCs from the Request for Comments Web site.)

See also

• WriteBase64(Byte[], Int32, Int32)
• XmlReader