Enumerable.Where<TSource> Method (IEnumerable<TSource>, Func<TSource, Int32, Boolean>)
Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function.
Assemblies: System.Linq (in System.Linq.dll)
System.Core (in System.Core.dll)
public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, int, bool> predicate )
The type of the elements of source.
Return ValueType: System.Collections.Generic.IEnumerable<>
An IEnumerable<T> that contains elements from the input sequence that satisfy the condition.
Usage NoteIn Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.
The first argument of predicate represents the element to test. The second argument represents the zero-based index of the element within source.
The following code example demonstrates how to use to filter a sequence based on a predicate that involves the index of each element.
.NET FrameworkSupported in: 4.6, 4.5, 4, 3.5
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
XNA FrameworkSupported in: 3.0
Portable Class LibrarySupported in: Portable Class Library
Supported in: Windows Phone 8.1
Supported in: Windows Phone Silverlight 8.1
Supported in: Windows Phone Silverlight 8