c#实现四舍五入

1.代码实现

        /// <summary>
        /// 保留小数位数，实现四舍五入
        /// </summary>
        /// <param name="number">数字</param>
        /// <param name="decimalNumber">保留位数</param>
        /// <returns></returns>
private  decimal SignificantDecimal(decimal number, int decimalNumber)
        {
            string numberStr = number.ToString();
            int dotIndex = numberStr.IndexOf('.');
            if (dotIndex < 0)
            {
                return number;
            }
            int firstNoneZeroIndex = numberStr.IndexOfAny(new char[] { '1', '2', '3', '4', '5', '6', '7', '8', '9' });
            int beginIndex = 0;
            if (dotIndex < firstNoneZeroIndex)
            {
                beginIndex = firstNoneZeroIndex;
            }
            else
            {
                beginIndex = dotIndex + 1;
            }
            decimal result = Round(number, beginIndex - dotIndex + decimalNumber - 1);
            return result;
        }

        private  decimal Round(decimal number, int decimalNumber)
        {
            return Math.Round(number, decimalNumber, MidpointRounding.AwayFromZero);
          
        }

2. 使用

 decimal   mj1 = SignificantDecimal(0.224,2);