KeyedCollection String is insensitive

Question

Tried to follow the documentation, and I can't get it to work. Have a KeyedCollection with a key string.

How to make string key case insensitive in KeyedCollection?

In the dictionary, you can simply pass StringComparer.OrdinalIgnoreCase to ctor.

private static WordDefKeyed wordDefKeyed = new WordDefKeyed(StringComparer.OrdinalIgnoreCase); // this fails public class WordDefKeyed : KeyedCollection<string, WordDef> { // The parameterless constructor of the base class creates a // KeyedCollection with an internal dictionary. For this code // example, no other constructors are exposed. // public WordDefKeyed() : base() { } public WordDefKeyed(IEqualityComparer<string> comparer) : base(comparer) { // what do I do here??????? } // This is the only method that absolutely must be overridden, // because without it the KeyedCollection cannot extract the // keys from the items. The input parameter type is the // second generic type argument, in this case OrderItem, and // the return value type is the first generic type argument, // in this case int. // protected override string GetKeyForItem(WordDef item) { // In this example, the key is the part number. return item.Word; } } private static Dictionary<string, int> stemDef = new Dictionary<string, int(StringComparer.OrdinalIgnoreCase); // this works this is what I want for KeyedCollection 

Answer 1

If you want your WordDefKeyed type to be case insensitive by default, then your constructor without parameters without a space should pass an IEqualityComparer<string> instance to it, for example:

 public WordDefKeyed() : base(StringComparer.OrdinalIgnoreCase) { } 

StringComparer class has several standard implementations of IEqualityComparer<T> , which are usually used depending on the type of data you store:

• StringComparer.Ordinal and StringComparer.OrdinalIgnoreCase - Used when you use machine-readable strings, not strings that are entered or displayed to the user.

• StringComparer.InvariantCulture and StringComparer.CultureInvariantIgnoreCase - Used when you use strings that will not be displayed in the user interface but are culture sensitive and may be the same in different cultures.

• StringComparer.CurrentCulture and StringComparer.CurrentCultureIgnoreCase - Use for strings that are related to the current culture, for example, when you collect user input.

If you need StringComparer for a culture other than the current culture, you can call the static Create method to create a StringComparer for the specific CultureInfo .