比较两个长度不同的字符串列表，以根据内容而不是长度进行区别

Question

I have two lists, imported and existing . They can be of the same length, or of different length.

I want to check if there's anything in imported that's not in existing .

If they're the same length, I'm able to compare them and find a mismatch with the following:

if(Enumerable.SequenceEqual(imported.OrderBy(i => i), existing.OrderBy(ex => ex)) == false)

If the lists are the same length, the above works as expected. If not, it doesn't as one contains items the other doesn't, which makes sense.

How can I do this for lists of different lengths?

Scenario A , should pass, there's nothing in imported that's not in existing :

Existing: "One", "Two", "Three"

Imported: "One","Two"

Scenario B , should fail, "Two" is in imported but it's not in existing :

Existing: "One", "Two", "Three"

Imported: "One","Tow"

I've used Intersect , Except and Any but they will work on Scenario A and not B, or vice versa.

Answer 1

imported.Except(existing).Any();

Answer 2

Enumerable.Except could be your tool

List<string> imported = new List<string>() {"One", "Two", "Three"};
List<string> existing = new List<string>() {"One", "Two", "Four"};

List<string>missing = imported.Except(existing, 
                      StringComparer.CurrentCultureIgnoreCase).ToList();
if(missing.Count == 0)
    Console.WriteLine("Nothing to import");
else
    Console.WriteLine("There are " + missing.Count + " items to import");

Of course, this answer assumes that you have something to do with the resulting difference (if any). Otherwise the asnwers using Any are more direct to you question

Answer 3

这可能会有所帮助：

imported.Any(i=>!existing.Contains(i));

Answer 4

if (imported.Any(item => !existing.Contains(item)))
    ...

Answer 5

通过填充null或字符串使两个列表具有相同的长度怎么办？清空缺少的位置？