C#中格式化小数位数为指定位数的工具类

旧城等待， 2023-10-06 10:23 22阅读 0赞

## 场景 ##

C\#中怎样格式化小数位数为指定位数的工具类。

注：

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## 实现 ##

首先新建工具类DataProcessor，然后在工具类下新建方法FormatFloatValue

/// <summary>
            /// 格式化小数位数
            /// </summary>
            /// <param name="floatValue">要格式化的小数对象</param>
            /// <param name="maxPrecision">保留的最大小数位数</param>
            /// <returns>返回格式化后的小数字符串值</returns>
            public static object FormatFloatValue(object floatValue, int maxPrecision)
            {
                if (IsNullOrEmpty(floatValue))
                {
                    return String.Empty;
                }
                else
                {
                    int intPrecision = GetValidPrecision(floatValue, maxPrecision);
                    return String.Format("{0:f" + intPrecision + "}", floatValue);
                }
            }

其中用到了获取浮点数值的有效小数位数的方法GetValidPrecision

/// <summary>
            /// 获取浮点数值的有效小数位数
            /// </summary>
            /// <param name="value">浮点数值</param>
            /// <param name="maxPrecision">允许返回的最大小数位数</param>
            /// <returns>返回有效小数位数</returns>
            public static int GetValidPrecision(object value, int maxPrecision)
            {
                if (DataProcessor.IsNullOrEmpty(value))
                {
                    return 0;
                }
                else
                {
                    if (value.ToString().IndexOf(".") == -1)
                    {
                        return 0;
                    }
                    else
                    {
                        string strValue = value.ToString();
                        string precision = strValue.Substring(strValue.IndexOf(".") + 1);
                        int cnt = 0;    //保存末尾0的个数
                        for (int i = precision.Length - 1; i > 0; i--)
                        {
                            if (precision.ToCharArray()[i] == '0')
                            {
                                cnt++;
                            }
                            else
                            {
                                break;
                            }
                        }
                        int result = precision.Length - cnt;    //为有效小数位数
                        if (result > maxPrecision)
                        {
                            return maxPrecision;
                        }
                        else
                        {
                            return result;
                        }
                    }
                }
            }

这其中又用到了判空的方法IsNullOrEmpty

/// <summary>
            /// 判断是否为空
            /// </summary>
            /// <param name="value">要判断的对象</param>
            /// <returns>为空返回true，否则返回false</returns>
            public static bool IsNullOrEmpty(object value)
            {
                if (value == null || value == DBNull.Value || string.IsNullOrWhiteSpace(value.ToString()))
                {
                    return true;
                }
                return false;
            }

### 调用示例 ###

object value = DataProcessor.FormatFloatValue(obj, 3);

表示要将小数格式为3为小数位数。

### 效果 ###

格式化前

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]

格式化后

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

[https_blog.csdn.net_badao_liumang_qizhi]: https://blog.csdn.net/badao_liumang_qizhi
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200605112347924.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20200605112351476.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70