Question

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C# dictionary type with unique keys and values

I would like to make sure that a dictionary has unique keys AND values. Is there any way to add this kind of validation outside of building my own class? That is the only way I can think of accomplishing validation for values in a dictionary. But, maybe there is some attribute I could add that I cannot seem to find via google.

I am looking to use this dictionary with WPF bindings, if that helps, also.

Answer 1

Dictionary keys are unique, by definition. Ensuring dictionary values are unique is done the same way you’d check every array or collection member is unique.

.NET 3.5 introduces HashSet<T> which speeds things up, assuming your TValue type implements Equals(TValue).

HashSet<TValue> seenValues = new HashSet<TValue>();
foreach(TKey key in myDictionary) {
    if( seenValues .Contains( myDictionary[key] ) ) throw new Exception("Dictionary contains duplicate item.");
    seenValues .Add( myDictionary[key] );
}