如何在C＃中区分两个列表？ [英] How to get difference between two list in C#?

问题描述

大家好



我有两个列表我希望在第三个列表中获得两个列表的区别。 我的第一个清单null null。



我尝试过：

列表< long？> RateCardList = new List< long？>（）; 
列表< long> categorylist = new List< long>（）; 

列表< long？> ThirdList = new List< long？>（）;

 ThirdList = RateCardList.Except（categorylist）; 

我在ThirdList中遇到错误

解决方案

你得到错误，因为你的参数除了有 long 值，而不是RateListCard，持有 long？ s。



这样做：

 ThirdList = RateCardList.Except（categoryList.Select（x = >   new   long ？（x）））; 

.Select（x => new long？（x））获取所有元素，调用代码使它们 long？ s并返回一个新的 IEnumerable< long？> ，您可以有效地传递给 。

Hi All

I have two List I wanted to get difference of two list in 3rd list. my 1st list null able.

What I have tried:

List<long?> RateCardList = new List<long?>();
                List<long> categorylist = new List<long>();

List<long?> ThirdList = new List<long?>();

ThirdList = RateCardList.Except(categorylist);

I am getting error in ThirdList

解决方案

You get the error because your argument to Except has long values, as opposed to RateListCard, that holds long?s.

Do this:

ThirdList = RateCardList.Except(categoryList.Select(x => new long?(x)));

.Select(x => new long?(x)) takes all elements, calls the code to make them long?s and returns a new IEnumerable<long?>, which you can validly pass to Except.

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