Enumerable.Max(Of TSource) Method (IEnumerable(Of TSource), Func(Of TSource, Int32))
Invokes a transform function on each element of a sequence and returns the maximum Int32 value.
Assembly: System.Core (in System.Core.dll)
'Declaration <ExtensionAttribute> _ Public Shared Function Max(Of TSource) ( _ source As IEnumerable(Of TSource), _ selector As Func(Of TSource, Integer) _ ) As Integer 'Usage Dim source As IEnumerable(Of TSource) Dim selector As Func(Of TSource, Integer) Dim returnValue As Integer returnValue = source.Max(selector)
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Collections.Generic.IEnumerable(Of TSource)
A sequence of values to determine the maximum value of.
- selector
- Type: System.Func(Of TSource, Int32)
A transform function to apply to each element.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of TSource). 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).| Exception | Condition |
|---|---|
| ArgumentNullException | source or selector is Nothing. |
| InvalidOperationException | source contains no elements. |
The Max(Of TSource)(IEnumerable(Of TSource), Func(Of TSource, Int32)) method uses the Int32 implementation of IComparable(Of T) to compare values.
You can apply this method to a sequence of arbitrary values if you provide a function, selector, that projects the members of source into a numeric type, specifically Int32.
In Visual Basic query expression syntax, an Aggregate Into Max() clause translates to an invocation of Max.
The following code example demonstrates how to use Max(Of TSource)(IEnumerable(Of TSource), Func(Of TSource, Int32)) to determine the maximum value in a sequence of projected values.
Structure Pet Public Name As String Public Age As Integer End Structure Sub MaxEx4() ' Create an array of Pet objects. Dim pets() As Pet = {New Pet With {.Name = "Barley", .Age = 8}, _ New Pet With {.Name = "Boots", .Age = 4}, _ New Pet With {.Name = "Whiskers", .Age = 1}} ' Determine the "maximum" pet by passing a ' lambda expression to Max() that sums the pet's age ' and name length. Dim max As Integer = pets.Max(Function(pet) _ pet.Age + pet.Name.Length) ' Display the result. MsgBox("The maximum pet age plus name length is " & max) End Sub ' This code produces the following output: ' ' The maximum pet age plus name length is 14
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The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.