上网乱转悠，看到这个 C#将10进制转换为16进制自写的方法  delphine的专栏

http://blog.csdn.net/delphine/archive/2005/07/19/428552.aspx

引用 public class CryptString  {   /// <summary>   /// 返回１６进制字符   /// </summary>   /// <param name="value">value</param>   /// <returns></returns>   public static string GetHexChar(string value)   {    string sReturn = string.Empty;    switch(value)    {     case "10":      sReturn = "A";      break;     case "11":      sReturn = "B";      break;     case "12":      sReturn = "C";      break;     case "13":      sReturn = "D";      break;     case "14":      sReturn = "E";      break;     case "15":      sReturn = "F";      break;     default :      sReturn = value;      break;    }    return sReturn;   }     /// <summary>   /// 返回１６进制   /// </summary>   /// <param name="value">value</param>   /// <returns></returns> public static string ConvertHex(string value)   {    string sReturn = string.Empty;    try    {         while(int.Parse(value)>16)     {      int v = int.Parse(value);      sReturn=GetHexChar((v%16).ToString())+sReturn;      value=Math.Floor(Convert.ToDouble(v/16)).ToString();     }     sReturn=GetHexChar(value)+sReturn;    }    catch    {     sReturn="###Valid Value!###";    }    return sReturn;   }   }

一时手痒，想了两个方法：

string s="2345435";
int i=int.Parse(s);
Trace.WriteLine(i.ToString("X"));

public static string GetHexChar(string value)
{
 string sReturn = string.Empty;
 if(int.Parse(value)>=10)
  sReturn=((char)('A'+int.Parse(value)-10)).ToString();
 else
  sReturn = value;
 return sReturn;
}