无尽的(几乎)字母数字计数器

Question

试图在此线程[ 字母数字计数器 ] 的答案的基础上构建一个无填充的无尽(对于任何int)字母数字计数器.

我想创建一个从0开始计数的计数器.

0,1,2 ... Y,Z,10,11,12 ... 1Y,1Z,20,21 ... ZY,ZZ,100,101 ... ZZZ,1000,1001 ..无穷大(溢流). ...

计数器的目的是从我的数据库INTID 创建短URL .我想输入行的id并从中获取基数36值,我可以将其用作url.

我做了几次尝试,但他们似乎都错了.当我应该增加字符数时,我会陷入困境.即从Z到10或从ZZ到100.

Answer 1

我想这就是你想要的:

using System;
using System.Collections.Generic;

class Test
{
    static void Main()
    {
        foreach (string x in EndlessBase64Sequence())
        {
            Console.WriteLine(x);
        }
    }

    private static char NextBase36Char(char c)
    {
        if ((c >= '0' && c <= '8') ||
            (c >= 'A' && c <= 'Z'))
        {
            return (char) (c + 1);
        }
        if (c == '9')
        {
            return 'A';
        }
        throw new ArgumentException();
    }

    public static IEnumerable<string> EndlessBase64Sequence()
    {
        char[] chars = { '0' };

        while (true)
        {
            yield return new string(chars);

            // Move to the next one...
            bool done = false;
            for (int position = chars.Length - 1; position >= 0; position--)
            {
                if (chars[position] == 'Z')
                {
                    chars[position] = '0';
                }
                else
                {
                    done = true;
                    chars[position] = NextBase36Char(chars[position]);
                    break;
                }
            }
            // Need to expand?
            if (!done)
            {
                chars = new char[chars.Length + 1];
                chars[0] = '1';
                for (int i = 1; i < chars.Length; i++)
                {
                    chars[i] = '0';
                }
            }
        }
    }
}