如何在三元运算符的else部分做“无”

Question

我想根据列表的值是否包含在其他列表中来过滤列表的值。如果一个元素在列表中，我将选择它，否则我想跳过它或基本上什么都不做。

以下是我尝试做的事情。我怎样才能做到这一点？

List<string> sheetNames = new List<string>() {"1","10"};
List<string> projects= new List<string>() {"1","2","3","4","5","6","7"};

IEnumerable<string> result =  
    sheetNames.Select(x => projects.Contains(x) 
                               ? x 
                               : /*Want to do nothing here */);

Answer 1

您可以使用Enumerable.Intersect方法从两个列表中获取常用值。

IEnumerable<string> commonValues = projects.Intersect(sheetNames);

Answer 2

List<string> sheetNames = new List<string>() {"1","10"};
List<string> projects= new List<string>() {"1","2","3","4","5","6","7"};

IEnumerable<string> result = sheetNames.Where(x => projects.Contains(x));