Convert.ToBase64CharArray Method (Byte(), Int32, Int32, Char(), Int32)

 

Converts a subset of an 8-bit unsigned integer array to an equivalent subset of a Unicode character array encoded with base-64 digits. Parameters specify the subsets as offsets in the input and output arrays, and the number of elements in the input array to convert.

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

Public Shared Function ToBase64CharArray (
	inArray As Byte(),
	offsetIn As Integer,
	length As Integer,
	outArray As Char(),
	offsetOut As Integer
) As Integer

Parameters

inArray
Type: System.Byte()

An input array of 8-bit unsigned integers.

offsetIn
Type: System.Int32

A position within inArray.

length
Type: System.Int32

The number of elements of inArray to convert.

outArray
Type: System.Char()

An output array of Unicode characters.

offsetOut
Type: System.Int32

A position within outArray.

Return Value

Type: System.Int32

A 32-bit signed integer containing the number of bytes in outArray.

Exception Condition
ArgumentNullException

inArray or outArray is null.

ArgumentOutOfRangeException

offsetIn, offsetOut, or length is negative.

-or-

offsetIn plus length is greater than the length of inArray.

-or-

offsetOut plus the number of elements to return is greater than the length of outArray.

The subset of length elements of inArray starting at position offsetIn, are taken as a numeric value and converted to a subset of elements in outArray starting at position offsetOut. The return value indicates the number of converted elements in outArray. The subset of outArray consists of base-64 digits.

The base-64 digits in ascending order from zero are the uppercase characters "A" to "Z", the lowercase characters "a" to "z", the numerals "0" to "9", and the symbols "+" and "/". The valueless character, "=", is used for trailing padding.

The offset and length parameters are 32-bit signed numbers. The offsetIn and offsetOut parameters are zero-based array positions.

System_CAPS_importantImportant

The ToBase64CharArraymethod is designed to process a single byte array that contains all the data to be encoded. To create a base-64 character array from a byte stream, use the System.Security.Cryptography.ToBase64Transform class.

The following example demonstrates using the ToBase64CharArray method to UUencode (encode in base 64) a binary stream, then save the encoding to a file.

Public Sub EncodeWithCharArray()
   Dim inFile As System.IO.FileStream
   Dim binaryData() As Byte

   Try
      inFile = New System.IO.FileStream(inputFileName, _
                                        System.IO.FileMode.Open, _
                                        System.IO.FileAccess.Read)
      ReDim binaryData(inFile.Length)
      Dim bytesRead As Long = inFile.Read(binaryData, _
                                          0, _
                                          CInt(inFile.Length))
      inFile.Close()
   Catch exp As System.Exception
      ' Error creating stream or reading from it.
      System.Console.WriteLine("{0}", exp.Message)
      Return
   End Try

   ' Convert the binary input into Base64 UUEncoded output.
   ' Each 3 byte sequence in the source data becomes a 4 byte
   ' sequence in the character array. 
   Dim arrayLength As Long 
   arrayLength = (4 / 3) * binaryData.Length
   If arrayLength Mod 4 <> 0 Then
      arrayLength = arrayLength + 4 - arrayLength Mod 4
   End If

   Dim base64CharArray(arrayLength - 1) As Char
   Try
      System.Convert.ToBase64CharArray(binaryData, _
                                       0, _
                                       binaryData.Length, _
                                       base64CharArray, 0)
   Catch exp As System.ArgumentNullException
      System.Console.WriteLine("Binary data array is null.")
      Return
   Catch exp As System.ArgumentOutOfRangeException
      System.Console.WriteLine("Char Array is not large enough.")
      Return
   End Try

   ' Write the UUEncoded version to the output file.
   Dim outFile As System.IO.StreamWriter
   Try
      outFile = New System.IO.StreamWriter(outputFileName, _
                                           False, _
                                           System.Text.Encoding.ASCII)
      outFile.Write(base64CharArray)
      outFile.Close()
   Catch exp As System.Exception
      ' Error creating stream or writing to it.
      System.Console.WriteLine("{0}", exp.Message)
   End Try
End Sub

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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