using System;

using System.Runtime.InteropServices;

using System.Buffers.Text;

​

public class Program

{

    public static void Main()

    {

        Guid gd = Guid.NewGuid();

        Console.WriteLine(gd.ToString());

        var gds = BetterToStringFromGuid(gd);

        Console.WriteLine(gds);

        Console.WriteLine(BetterToGuidFromString(gds).ToString());

    }

​

    //Helps to use the Guids in URL 

    //Version 1

    public static string ToStringFromGuid(Guid guid)

    {

        return Convert.ToBase64String(guid.ToByteArray()).Replace("/", "-").Replace("+", "_").Replace("=", string.Empty);

    }

​

    public static string BetterToStringFromGuid(Guid guid)

    {

        Span<byte> idBytes = stackalloc byte[16];

        Span<byte> base64bytes = stackalloc byte[24];

        MemoryMarshal.TryWrite(idBytes, ref guid);

        Base64.EncodeToUtf8(idBytes, base64bytes, out _, out _);

        Span<char> base64Chars = stackalloc char[24];

        for (int i = 0; i < 22; i++)

        {

            base64Chars[i] = base64bytes[i] switch

            {

                (byte)'/' => '-',

                (byte)'+' => '_',

                _ => (char)base64bytes[i]

            };

        }

​

        return new string (base64Chars);

    }

​

    //Version 1

    public static Guid ToGuidFromString(string formatttedGuid)

    {

        var guid = Convert.FromBase64String(formatttedGuid.Replace("-", "/").Replace("_", "+") + "==");

        return new Guid(guid);

    }

​

    private const char EqualsChar = '=';

    //Convert to Guid using stack memory instead of Heap memory allocation

    public static Guid BetterToGuidFromString(ReadOnlySpan<char> formatttedGuid)

    {

        Span<char> base64Chars = stackalloc char[24];

        for (int i = 0; i < 22; i++)

        {

            base64Chars[i] = formatttedGuid[i] switch

            {

                '-' => '/',

                '_' => '+',

                _ => formatttedGuid[i]

            };

        }

​

        base64Chars[22] = EqualsChar;

        base64Chars[23] = EqualsChar;

        Span<byte> idBytes = stackalloc byte[16];

        Convert.TryFromBase64Chars(base64Chars, idBytes, out _);

        return new Guid(idBytes);

    }

}