using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

​

            var betIds = new string[]

        {// 添加其他 betId 字串...

            "AIBQAAQAVLL5MIQAAAAABCIOAAAA",

            "AIBQACAADB3ROIYAAAAAANYBAAAA",

            "AIBQAAQAYCLWOGYAAAAAAUQYAAAA",

​

        };

​

        foreach (var betId in betIds)

        {

            var bytes = Base32.ToBytes(betId);

            bytes = bytes.Skip(13).Take(4).ToArray();

            var i = BitConverter.ToInt32(bytes, 0);

            Console.WriteLine($"betId: {betId}, TransNum: {i}");

        }

    }

    public class Base32

    {

        public static byte[] ToBytes(string input)

        {

            if (string.IsNullOrEmpty(input))

            {

                throw new ArgumentNullException("input");

            }

​

            input = input.TrimEnd('='); //remove padding characters

            int byteCount = input.Length * 5 / 8; //this must be TRUNCATED

            byte[] returnArray = new byte[byteCount];

​

            byte curByte = 0, bitsRemaining = 8;

            int mask = 0, arrayIndex = 0;

​

            foreach (char c in input)

            {

                int cValue = CharToValue(c);

​

                if (bitsRemaining > 5)

                {

                    mask = cValue << (bitsRemaining - 5);

                    curByte = (byte) (curByte | mask);

                    bitsRemaining -= 5;

                }

                else

                {

                    mask = cValue >> (5 - bitsRemaining);

                    curByte = (byte) (curByte | mask);

                    returnArray[arrayIndex++] = curByte;

                    curByte = (byte) (cValue << (3 + bitsRemaining));

                    bitsRemaining += 3;

                }

            }

​

            //if we didn't end with a full byte

            if (arrayIndex != byteCount)

            {

                returnArray[arrayIndex] = curByte;

            }

​

            return returnArray;

        }

​

        public static string ToString(byte[] input)

        {

            if (input == null || input.Length == 0)

            {

                throw new ArgumentNullException("input");

            }

​

            int charCount = (int) Math.Ceiling(input.Length / 5d) * 8;

            char[] returnArray = new char[charCount];

​

            byte nextChar = 0, bitsRemaining = 5;

            int arrayIndex = 0;

​

            foreach (byte b in input)

            {

                nextChar = (byte) (nextChar | (b >> (8 - bitsRemaining)));

                returnArray[arrayIndex++] = ValueToChar(nextChar);

​

                if (bitsRemaining < 4)

                {

                    nextChar = (byte) ((b >> (3 - bitsRemaining)) & 31);

                    returnArray[arrayIndex++] = ValueToChar(nextChar);

                    bitsRemaining += 5;

                }

​

                bitsRemaining -= 3;

                nextChar = (byte) ((b << bitsRemaining) & 31);

            }

​

            //if we didn't end with a full char

            if (arrayIndex != charCount)

            {

                returnArray[arrayIndex++] = ValueToChar(nextChar);

                while (arrayIndex != charCount) returnArray[arrayIndex++] = '='; //padding

            }

​

            return new string(returnArray);

        }

​

        private static int CharToValue(char c)

        {

            int value = (int) c;

​

            //65-90 == uppercase letters

            if (value < 91 && value > 64)

            {

                return value - 65;

            }

​

            //50-55 == numbers 2-7

            if (value < 56 && value > 49)

            {

                return value - 24;

            }

​

            //97-122 == lowercase letters

            if (value < 123 && value > 96)

            {

                return value - 97;

            }

​

            throw new ArgumentException("Character is not a Base32 character.", "c");

        }

​

        private static char ValueToChar(byte b)

        {

            if (b < 26)

            {

                return (char) (b + 65);

            }

​

            if (b < 32)

            {

                return (char) (b + 24);

            }

​

            throw new ArgumentException("Byte is not a value Base32 value.", "b");

        }

    }

}