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List<T>.ConvertAll<TOutput> Method

Converts the elements in the current List<T> to another type, and returns a list containing the converted elements.

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

public List<TOutput> ConvertAll<TOutput>(
	Converter<T, TOutput> converter
)

Type Parameters

TOutput

The type of the elements of the target array.

Parameters

converter
Type: System.Converter<T, TOutput>

A Converter<TInput, TOutput> delegate that converts each element from one type to another type.

Return Value

Type: System.Collections.Generic.List<TOutput>
A List<T> of the target type containing the converted elements from the current List<T>.

ExceptionCondition
ArgumentNullException

converter is null.

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

The current List<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<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<TOutput> method. The ConvertAll<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.

using System;
using System.Drawing;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<PointF> lpf = new List<PointF>();

        lpf.Add(new PointF(27.8F, 32.62F));
        lpf.Add(new PointF(99.3F, 147.273F));
        lpf.Add(new PointF(7.5F, 1412.2F));

        Console.WriteLine();
        foreach( PointF p in lpf )
        {
            Console.WriteLine(p);
        }

        List<Point> lp = lpf.ConvertAll( 
            new Converter<PointF, Point>(PointFToPoint));

        Console.WriteLine();
        foreach( Point p in lp )
        {
            Console.WriteLine(p);
        }
    }

    public static Point PointFToPoint(PointF pf)
    {
        return new Point(((int) pf.X), ((int) pf.Y));
    }
}

/* 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=27,Y=32}
{X=99,Y=147}
{X=7,Y=1412}
 */

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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