C# decimal保留指定的小数位数，不四舍五入

 1 public static class DecimalExtension
 2     {
 3         /// <summary>
 4         /// decimal保留指定位数小数
 5         /// </summary>
 6         /// <param name="num">原始数量</param>
 7         /// <param name="scale">保留小数位数</param>
 8         /// <returns>截取指定小数位数后的数量字符串</returns>
 9         public static string ToString(this decimal num, int scale)
10         {
11             string numToString = num.ToString();
12 
13             int index = numToString.IndexOf(".");
14             int length = numToString.Length;
15 
16             if (index != -1)
17             {
18                 return string.Format("{0}.{1}",
19                     numToString.Substring(0, index),
20                     numToString.Substring(index + 1, Math.Min(length - index - 1, scale)));
21             }
22             else
23             {
24                 return num.ToString();
25             }
26         }
27     }