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ConvertAll(TOutput) Method

List(Of T).ConvertAll(Of TOutput) Method

Converts the elements in the current List(Of T) to another type, and returns a list containing the converted elements.

Namespace:  System.Collections.Generic
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public Function ConvertAll(Of TOutput) ( _
	converter As Converter(Of T, TOutput) _
) As List(Of TOutput)

Type Parameters

TOutput

The type of the elements of the target array.

Parameters

converter
Type: System.Converter(Of T, TOutput)

A Converter(Of TInput, TOutput) delegate that converts each element from one type to another type.

Return Value

Type: System.Collections.Generic.List(Of TOutput)
A List(Of T) of the target type containing the converted elements from the current List(Of T).

ExceptionCondition
ArgumentNullException

converter is Nothing.

The Converter(Of TInput, TOutput) is a delegate to a method that converts an object to the target type. The elements of the current List(Of T) are individually passed to the Converter(Of TInput, TOutput) delegate, and the converted elements are saved in the new List(Of T).

The current List(Of T) remains unchanged.

This method is an O(n) operation, where n is Count.

The following example defines a method named PointFToPoint that converts a PointF structure to a Point structure. The example then creates a List(Of T) of PointF structures, creates a Converter<PointF, Point> delegate (Converter(Of PointF, Point) in Visual Basic) to represent the PointFToPoint method, and passes the delegate to the ConvertAll(Of TOutput) method. The ConvertAll(Of TOutput) method passes each element of the input list to the PointFToPoint method and puts the converted elements into a new list of Point structures. Both lists are displayed.

Imports System
Imports System.Drawing
Imports System.Collections.Generic

Public Class Example

    Public Shared Sub Main()

        Dim lpf As New List(Of PointF)

        lpf.Add(New PointF(27.8, 32.62))
        lpf.Add(New PointF(99.3, 147.273))
        lpf.Add(New PointF(7.5, 1412.2))

        Console.WriteLine()
        For Each p As PointF In lpf
            Console.WriteLine(p)
        Next 

        Dim lp As List(Of Point) = lpf.ConvertAll( _
            New Converter(Of PointF, Point)(AddressOf PointFToPoint))

        Console.WriteLine()
        For Each p As Point In lp
            Console.WriteLine(p)
        Next 

    End Sub 

    Public Shared Function PointFToPoint(ByVal pf As PointF) _
        As Point

        Return New Point(CInt(pf.X), CInt(pf.Y))
    End Function 
End Class 

' This code example produces the following output: 

'{X=27.8, Y=32.62} 
'{X=99.3, Y=147.273} 
'{X=7.5, Y=1412.2} 

'{X=28,Y=33} 
'{X=99,Y=147} 
'{X=8,Y=1412}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0
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