Enumerable::ToDictionary<TSource, TKey, TElement> Method (IEnumerable<TSource>^, Func<TSource, TKey>^, Func<TSource, TElement>^, IEqualityComparer<TKey>^)
Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function, a comparer, and an element selector function.
Assembly: System.Core (in System.Core.dll)
public: generic<typename TSource, typename TKey, typename TElement> [ExtensionAttribute] static Dictionary<TKey, TElement>^ ToDictionary( IEnumerable<TSource>^ source, Func<TSource, TKey>^ keySelector, Func<TSource, TElement>^ elementSelector, IEqualityComparer<TKey>^ comparer )
Parameters
- source
-
Type:
System.Collections.Generic::IEnumerable<TSource>^
An IEnumerable<T> to create a Dictionary<TKey, TValue> from.
- keySelector
-
Type:
System::Func<TSource, TKey>^
A function to extract a key from each element.
- elementSelector
-
Type:
System::Func<TSource, TElement>^
A transform function to produce a result element value from each element.
- comparer
-
Type:
System.Collections.Generic::IEqualityComparer<TKey>^
An IEqualityComparer<T> to compare keys.
Return Value
Type: System.Collections.Generic::Dictionary<TKey, TElement>^A Dictionary<TKey, TValue> that contains values of type TElement selected from the input sequence.
Type Parameters
- TSource
The type of the elements of source.
- TKey
The type of the key returned by keySelector.
- TElement
The type of the value returned by elementSelector.
| Exception | Condition |
|---|---|
| ArgumentNullException | source or keySelector or elementSelector is null. -or- keySelector produces a key that is null. |
| ArgumentException | keySelector produces duplicate keys for two elements. |
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1