.NET 是否有忽略大小写的 IComparer 实现<string> ?

Question

I have Dictionary<string, int> . I want to get my int value by string key, but ignore string case.

I just figured out, that I can use Dictionary<TKey,TValue> constructor with IComparer parameter and Dictionary will use it to compare keys.

But do I have to write IComparer<string> implementation myself?

Answer 1

Yes, the StringComparer class provides a bunch of convenient StringComparer instances (which implement IComparer<string> ) that does case-insensitive comparison:

• CurrentCultureIgnoreCase
• InvariantCultureIgnoreCase
• OrdinalIgnoreCase

Without knowing any more of your use case, I can't tell you which comparer you want to use. You need to think about which culture (or the invariant culture) you want the comparison to be in, or whether you want a simple ordinal comparison.

---

That said, Dictionary doesn't accept an IComparer , but an IEqualityComparer ... But you can still use StringComparer nonetheless, it also implements IEqualityComparer .