将十六进制数转换成十进制数

class Program
{
void ConvertToHex()
{
double n = 0;
Console.Write("输入十六进制数：");
string s = Console.ReadLine().ToLower();

if (s != "q")
{
byte[] b = Encoding.Default.GetBytes(s);
for (int i = 0; i < b.Length; i++)
{
if (b[i] > 96&&b[i]<103)
b[i] -= 87;
else if(b[i]>47&&b[i]<58)
b[i] -= 48;
else
Console.WriteLine("输入不合法");
}

for (int i = 0; i < s.Length; i++)
{
n += b[s.Length-1-i] * Math.Pow(16, i);
}

Console.WriteLine("{0}的十进制数：{1}",s ,n);
Console.WriteLine();
ConvertToHex();
}
}

static void Main(string[] args)
{
Program c = new Program();
Console.WriteLine("输入“Q”退出：");
c.ConvertToHex();
}

}