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Mike Cole
Mike Cole

Reputation: 14703

How can I make Array.Contains case-insensitive on a string array?

I am using the Array.Contains method on a string array. How can I make that case-insensitive?

Upvotes: 231

Views: 113567

Answers (5)

Porky
Porky

Reputation: 988

From a Powershell point of view, I like to keep things easy to read for everyone, so for:

$data = @('Zero','One','Two','Three')
$data -contains 'three'

will do a case insensitive check but

$data -ccontains 'three'

will be case sensitive. Hope that helps.

Upvotes: 0

Philm
Philm

Reputation: 3674

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))
{}

  1. 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;

  2. 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.

Upvotes: 14

Mehrdad Afshari
Mehrdad Afshari

Reputation: 421968

array.Contains("str", StringComparer.OrdinalIgnoreCase);

Or depending on the specific circumstance, you might prefer:

array.Contains("str", StringComparer.CurrentCultureIgnoreCase);
array.Contains("str", StringComparer.InvariantCultureIgnoreCase);

Upvotes: 401

Kon
Kon

Reputation: 27431

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()))

Upvotes: 0

Darin Dimitrov
Darin Dimitrov

Reputation: 1038710

new[] { "ABC" }.Select(e => e.ToLower()).Contains("abc") // returns true

Upvotes: 0

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