字符串去重/C#

方法一： 

str_leader = string.Join(",", str_leader.Split(',').Distinct().ToArray()); //需要.NET 3.5框架支持

方法二：正则

using System.Text.RegularExpressions;    //为使用正则表达式类

str_leader = Regex.Replace(str_leader + ",", @"(?:([^,]+,))(?=.?\1)", "");