System.Linq.ILookup<TKey, TElement>

ILookup<TKey, TElement>

public interface ILookup<TKey, TElement> : IEnumerable<IGrouping<TKey, TElement>>, IEnumerable

Defines an indexer, size property, and Boolean search method for data structures that map keys to IEnumerable<T> sequences of values.

int Count { get; }

Gets the number of key/value collection pairs in the ILookup<T, U>.

IEnumerable<TElement> this[TKey key] { get; }

Gets the IEnumerable<T> sequence of values indexed by a specified key.

bool Contains(TKey key)

Determines whether a specified key exists in the ILookup<T, U>.