.net 如何在字符串数组上使 Array.Contains 不区分大小写？
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How can I make Array.Contains case-insensitive on a string array?
提问by Mike Cole
I am using the Array.Containsmethod on a string array. How can I make that case-insensitive?
我Array.Contains在字符串数组上使用该方法。我怎样才能使不区分大小写？
回答by Mehrdad Afshari
array.Contains("str", StringComparer.OrdinalIgnoreCase);
Or depending on the specific circumstance, you might prefer:
或者根据具体情况，您可能更喜欢：
array.Contains("str", StringComparer.CurrentCultureIgnoreCase);
array.Contains("str", StringComparer.InvariantCultureIgnoreCase);
回答by Philm
Some important notes from my side, or at least putting some distributed info at one place- concerning the tip above with a StringComparer like in:
我这边的一些重要说明，或者至少将一些分布式信息放在一个地方 - 关于上面带有 StringComparer 的提示，例如：
if (array.Contains("str", StringComparer.OrdinalIgnoreCase))
{}
array.Contains()is a LINQ extension method and therefore works by standard only with .NET 3.5 or higher, needing:using System;using System.Linq;But: in .NET 2.0 the simple
Contains()method (without taking case insensitivity into account) is at least possible like this, with a cast:if ( ((IList<string>)mydotNet2Array).Contains(“str”) ) {}As the Contains() method is part of the IList interface, this works not only with arrays, but also with lists, etc.
array.Contains()是一种 LINQ 扩展方法，因此仅适用于 .NET 3.5 或更高版本的标准，需要：using System;using System.Linq;但是：在 .NET 2.0 中，简单的
Contains()方法（不考虑不区分大小写）至少可以像这样，使用强制转换：if ( ((IList<string>)mydotNet2Array).Contains(“str”) ) {}由于 Contains() 方法是 IList 接口的一部分，这不仅适用于数组，还适用于列表等。
回答by Kon
Implement a custom IEqualityComparerthat takes case-insensitivity into account.
实现一个自定义的IEqualityComparer，它考虑到不区分大小写。
Additionally, check thisout. So then (in theory) all you'd have to do is:
此外，检查这出。那么（理论上）你所要做的就是：
myArray.Contains("abc", ProjectionEqualityComparer<string>.Create(a => a.ToLower()))
回答by Darin Dimitrov
new[] { "ABC" }.Select(e => e.ToLower()).Contains("abc") // returns true
