Decodes the supplied Base-64 encoded string. - CSharp System

CSharp examples for System:String Base64

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Description

Decodes the supplied Base-64 encoded string.

Demo Code

// This library is free software; you can redistribute it and/or
using System.Text;
using System;/*  w  w w. j a v a  2  s  . co  m*/

public class Main{
    private static readonly string Alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    /// <summary>Decodes the supplied Base-64 encoded string.</summary>
      /// <remarks>Decodes the supplied Base-64 encoded string.</remarks>
      /// <param name="string">The Base-64 encoded string that is to be decoded.</param>
      /// <returns>A <code>byte[]</code> containing the decoded data block.</returns>
      public static byte[] Decode(string @string)
      {
         int length = @string.Length;
         if (length == 0)
         {
            return new byte[0];
         }
         int pad = (@string[length - 2] == '=') ? 2 : (@string[length - 1] == '=') ? 1 : 0;
         int size = length * 3 / 4 - pad;
         byte[] buffer = new byte[size];
         int block;
         int i = 0;
         int index = 0;
         while (i < length)
         {
            block = (Alphabet.IndexOf(@string[i++]) & unchecked(0xff)) << 18 | (Alphabet
               .IndexOf(@string[i++]) & unchecked(0xff)) << 12 | (Alphabet.IndexOf(@string
               [i++]) & unchecked(0xff)) << 6 | (Alphabet.IndexOf(@string[i++]) & unchecked(
               0xff));
            buffer[index++] = unchecked((byte)((int)(((uint)block) >> 16)));
            if (index < size)
            {
               buffer[index++] = unchecked((byte)(((int)(((uint)block) >> 8)) & unchecked(0xff)));
            }
            if (index < size)
            {
               buffer[index++] = unchecked((byte)(block & unchecked(0xff)));
            }
         }
         return buffer;
      }
}

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