From Base String to byte array - CSharp System

CSharp examples for System:Byte Array

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Description

From Base String to byte array

Demo Code


using System.Threading.Tasks;
using System.Text;
using System.Linq;
using System.Collections.Generic;
using System;//  w w  w .j  a v  a  2s .com

public class Main{
        static public byte[] FromBase64(string s)
        {
            int length = s == null ? 0 : s.Length;
            if (length == 0)
                return new byte[0];

            int padding = 0;
            if (length > 2 && s[length - 2] == '=')
                padding = 2;
            else if (length > 1 && s[length - 1] == '=')
                padding = 1;

            int blocks = (length - 1) / 4 + 1;
            int bytes = blocks * 3;

            byte[] data = new byte[bytes - padding];

            for (int i = 0; i < blocks; i++)
            {
                bool finalBlock = i == blocks - 1;
                bool pad2 = false;
                bool pad1 = false;
                if (finalBlock)
                {
                    pad2 = padding == 2;
                    pad1 = padding > 0;
                }

                int index = i * 4;
                byte temp1 = CharToSixBit(s[index]);
                byte temp2 = CharToSixBit(s[index + 1]);
                byte temp3 = CharToSixBit(s[index + 2]);
                byte temp4 = CharToSixBit(s[index + 3]);

                byte b = (byte)(temp1 << 2);
                byte b1 = (byte)((temp2 & 0x30) >> 4);
                b1 += b;

                b = (byte)((temp2 & 0x0F) << 4);
                byte b2 = (byte)((temp3 & 0x3C) >> 2);
                b2 += b;

                b = (byte)((temp3 & 0x03) << 6);
                byte b3 = temp4;
                b3 += b;

                index = i * 3;
                data[index] = b1;
                if (!pad2)
                    data[index + 1] = b2;
                if (!pad1)
                    data[index + 2] = b3;
            }

            return data;
        }
}

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