How can I make Array.Contains case-insensitive on a string array?
.Net.Net Problem Overview
I am using the Array.Contains
method on a string array. How can I make that case-insensitive?
.Net Solutions
Solution 1 - .Net
array.Contains("str", StringComparer.OrdinalIgnoreCase);
Or depending on the specific circumstance, you might prefer:
array.Contains("str", StringComparer.CurrentCultureIgnoreCase);
array.Contains("str", StringComparer.InvariantCultureIgnoreCase);
Solution 2 - .Net
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:
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.
Solution 3 - .Net
Implement a custom IEqualityComparer that takes case-insensitivity into account.
Additionally, check this out. So then (in theory) all you'd have to do is:
myArray.Contains("abc", ProjectionEqualityComparer<string>.Create(a => a.ToLower()))
Solution 4 - .Net
new[] { "ABC" }.Select(e => e.ToLower()).Contains("abc") // returns true