计算字符串和文件MD5值的小例子

//计算字符串的md5值
        public string getmd5(string sdatain)
        {
            md5cryptoserviceprovider md5 = new md5cryptoserviceprovider();
            byte[] bytvalue, bythash;
            bytvalue = system.text.encoding.utf8.getbytes(sdatain);
            bythash = md5.computehash(bytvalue);
            md5.clear();
            string stemp = "";
            for (int i = 0; i < bythash.length; i++)
            {
                stemp += bythash[i].tostring("x").padleft(2, '0');
            }
            return stemp.tolower();
        }
       

        //计算文件的md5值
        public string md5value(string filepath)
        {
            md5 md5 = new md5cryptoserviceprovider();
            byte[] md5ch;
            using (filestream fs = file.openread(filepath))
            {
                md5ch = md5.computehash(fs);
            }
            md5.clear();
            string strmd5 = "";
            for (int i = 0; i < md5ch.length - 1; i++)
            {
                strmd5 += md5ch[i].tostring("x").padleft(2, '0');
            }
            return strmd5;
        }