Case-INsensitive Dictionary with string key-type in C#

c# collections generic-collections
Mr. Boy picture Mr. Boy · Dec 21, 2012 · Viewed 61k times · Source

If I have a Dictionary<String,...> is it possible to make methods like ContainsKey case-insensitive?

This seemed related, but I didn't understand it properly: c# Dictionary: making the Key case-insensitive through declarations

Answer

Konrad Rudolph picture Konrad Rudolph · Dec 21, 2012

This seemed related, but I didn't understand it properly: c# Dictionary: making the Key case-insensitive through declarations

It is indeed related. The solution is to tell the dictionary instance not to use the standard string compare method (which is case sensitive) but rather to use a case insensitive one. This is done using the appropriate constructor:

var dict = new Dictionary<string, YourClass>(
        StringComparer.InvariantCultureIgnoreCase);

The constructor expects an IEqualityComparer which tells the dictionary how to compare keys.

StringComparer.InvariantCultureIgnoreCase gives you an IEqualityComparer instance which compares strings in a case-insensitive manner.

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