IEnumerableExtensionFirstOrNullTSource(IEnumerableTSource, FuncTSource, Boolean, Boolean) Method

public static TSource FirstOrNull<TSource>(
	this IEnumerable<TSource>? values,
	Func<TSource, bool>? filter,
	bool skipEmptyItems = true
)
where TSource : VCardProperty

<ExtensionAttribute>
Public Shared Function FirstOrNull(Of TSource As VCardProperty) ( 
	values As IEnumerable(Of TSource),
	filter As Func(Of TSource, Boolean),
	Optional skipEmptyItems As Boolean = true
) As TSource

public:
[ExtensionAttribute]
generic<typename TSource>
where TSource : VCardProperty
static TSource FirstOrNull(
	IEnumerable<TSource>^ values, 
	Func<TSource, bool>^ filter, 
	bool skipEmptyItems = true
)

[<ExtensionAttribute>]
static member FirstOrNull : 
        values : IEnumerable<'TSource> * 
        filter : Func<'TSource, bool> * 
        ?skipEmptyItems : bool 
(* Defaults:
        let _skipEmptyItems = defaultArg skipEmptyItems true
*)
-> 'TSource  when 'TSource : VCardProperty

Parameters

values  IEnumerableTSource

The IEnumerableT of VCardProperty objects to search. The collection may be null, empty, or may contain null references.

filter  FuncTSource, Boolean

A FuncT, TResult which allows additional filtering of the items, or null to not perform additional filtering. The arguments of the delegate are guaranteed to not be null.

skipEmptyItems  Boolean  (Optional)

Pass false to include empty items in the return value. ("Empty" means that IsEmpty returns true.) null values will always be ignored.

Type Parameters

TSource

Generic type parameter that's constrained to be a class that's derived from VCardProperty.

Return Value

The first VCardProperty from values that passes the filter, or null if no such item could be found. This happens in any case

• if values is null,
• if values is empty,
• if values contains only null references,
• or if values contains only empty items and skipEmptyItems is true.

"First" is defined as the item with the lowest Index value. If Index is null, MaxValue is assumed.

If no Index is specified, the first VCardProperty that passes the filter is returned.

Usage Note

Reference