C Sharp c# 10进制转化成36进制，其它任意进制。

把10进制转换成36进制，或者64进制。可以用更短的字符来表式更大范围的数据。

比如说我们的Url短连接。 在用6个字符就可以表达 68719476736这么大的空间。比int.MaxValue还大了.

还有我们早期的系统还会使用一些推荐码之类的。我们如果直接给出用户的ID或者名字，可能会让别人输入得很辛苦，所以我们可能就需要变成36进制。 这样别人输入的时候会方便一些。

public class ScaleConverter
    {
        private char[] chars;

        private Dictionary<char, int> dict;

        public int length;

        public ScaleConverter(string scaleString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ")
        {
            // OI 有一些字体的OI 跟 01是看不清楚的。 
            // 0123456789ABCDEFGHJKLMNPQRSTUVWXYZ
            this.chars = scaleString.ToCharArray();
            this.dict = ToCharDict(this.chars);
            this.length = this.chars.Length;
        }

        public string ToCurrent(int num)
        {
            string curr = "";
            while (num >= length)
            {
                curr = chars[num % length] + curr;
                num = num / length;
            }
            curr = chars[num] + curr;
            return curr;
        }

        public int ToInt32(string current)
        {
            double num = 0;
            for (int i = 0; i < current.Length; i++)
            {
                num += dict[current[i]] * Math.Pow(length, current.Length - 1 - i);
            }
            return  Convert.ToInt32(num);
        }

		// 跟据位数获取最小的数
		public int GetMinmumNumber(int length)
		{
			var minmumChars = new char[length];
			minmumChars[0] = chars[1];
			for (int i = 1; i < length; i++)
			{
				minmumChars[i]= chars[0];
			}
			return this.ToInt32(new string(minmumChars));
		}
	
        private static Dictionary<char, int> ToCharDict(char[] chars)
        {
            var dic = new Dictionary<char, int>();
            for (int i = 0; i < chars.Length; i++)
            {
                dic.Add(chars[i], i);
            }
            return dic;
        }
    }

推荐码有时候我们不希望这个代码从0开始。而是从1000开始。这样我就可以把这个"1000"转回我们的10进制数。让所有的用户ID加上这个数字，这样就可以达到这种效果了。

示例

void Main()
{
	var scale=  new ScaleConverter();
	var current = scale.ToCurrent(10000); //7ps
	var i = scale.ToInt32(current); //变成了10000
	Console.WriteLine(i+" "+current);
}

int64版本

 public class ScaleConverter
    {
        private char[] chars;

        private Dictionary<char, int> dict;

        public int length;

        /// <summary>
        /// scale chars does not have O and I
        /// </summary>
        /// <param name="scaleString"></param>
        public ScaleConverter(string scaleString = "0126789345BQPSUWRTVXYZADCFEHGJKLNM")
        {
            // normal string 0123456789ABCDEFGHJKLMNPQRSTUVWXYZ
            this.chars = scaleString.ToCharArray();
            this.dict = ToCharDict(this.chars);
            this.length = this.chars.Length;
        }

        public string ToCurrent(long num)
        {
            string curr = "";
            while (num >= length)
            {
                curr = chars[num % length] + curr;
                num = num / length;
            }
            curr = chars[num] + curr;
            return curr;
        }

        public long ToInt64(string current)
        {
            double num = 0;
            for (int i = 0; i < current.Length; i++)
            {
                num += dict[current[i]] * Math.Pow(length, current.Length - 1 - i);
            }
            return Convert.ToInt64(num);
        }

        public long GetMinmumNumber(int length)
        {   
			if (length < 1)
            {
                return 0;
            }
            var minmumChars = new char[length];
            minmumChars[0] = chars[1];
            for (int i = 1; i < length; i++)
            {
                minmumChars[i] = chars[0];
            }
            return this.ToInt64(new string(minmumChars));
        }
		
		public long GetMaximumNumber(int length)
		{
			if (length < 1)
            {
                return 0;
            }
			var maximumChars = new char[length];
			var lastChar =chars.Last();
			for (int i = 0; i < length; i++)
			{
				maximumChars[i] = lastChar;
			}
			return this.ToInt64(new string(maximumChars));
		}

        private static Dictionary<char, int> ToCharDict(char[] chars)
        {
            var dic = new Dictionary<char, int>();
            for (int i = 0; i < chars.Length; i++)
            {
                dic.Add(chars[i], i);
            }
            return dic;
        }
    }