Converter<TInput,TOutput> 委托

定义

表示将对象从一种类型转换为另一种类型的方法。Represents a method that converts an object from one type to another type.

generic <typename TInput, typename TOutput>
public delegate TOutput Converter(TInput input);
public delegate TOutput Converter<in TInput,out TOutput>(TInput input);
type Converter<'Input, 'Output> = delegate of 'Input -> 'Output
Public Delegate Function Converter(Of In TInput, Out TOutput)(input As TInput) As TOutput 

类型参数

TInput

要转换的对象的类型。The type of object that is to be converted.

TOutput

要将输入对象转换到的类型。The type the input object is to be converted to.

参数

input

要转换的对象。The object to convert.

返回值

TOutput

TOutput,它表示已转换的 TInputThe TOutput that represents the converted TInput.

继承
Converter<TInput,TOutput>

示例

本部分包含两个代码示例。This section contains two code examples. 第一个示例演示Converter<TInput,TOutput>了委托, ConvertAll其中包含Array类的方法, 第二个示例List<T>演示了具有ConvertAll泛型类的方法的委托。The first demonstrates the Converter<TInput,TOutput> delegate with the ConvertAll method of the Array class, and the second demonstrates the delegate with the ConvertAll method of the List<T> generic class.

示例 1Example 1

下面的代码示例定义了一个名PointFToPoint为的方法PointF , 该方法Point将结构转换为结构。The following code example defines a method named PointFToPoint that converts a PointF structure to a Point structure. 然后, 该示例PointF创建一个结构数组, Converter<PointF, Point>创建委托 (Converter(Of PointF, Point)在 Visual Basic 中) 以表示PointFToPoint方法, 并将委托传递给ConvertAll方法。The example then creates an array 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 method. 方法将输入列表的每个元素传递PointFToPoint给方法, 并将转换后的元素放入新的Point结构列表。 ConvertAllThe ConvertAll method passes each element of the input list to the PointFToPoint method and puts the converted elements into a new list of Point structures. 将显示这两个列表。Both lists are displayed.

#using <System.Drawing.dll>

using namespace System;
using namespace System::Drawing;
using namespace System::Collections::Generic;

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

void main()
{
    // Create an array of PointF objects.
    array<PointF>^ apf = {
        PointF(27.8F, 32.62F),
        PointF(99.3F, 147.273F),
        PointF(7.5F, 1412.2F) };


    // Display each element in the PointF array.
    Console::WriteLine();
    for each(PointF p in apf)
    {
        Console::WriteLine(p);
    }

    // Convert each PointF element to a Point object.
    array<Point>^ ap = 
        Array::ConvertAll(apf, 
            gcnew Converter<PointF, Point>(PointFToPoint)
        );

    // Display each element in the Point array.
    Console::WriteLine();
    for each(Point p in ap)
    {
        Console::WriteLine(p);
    }
}

/* 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}
 */
using System;
using System.Drawing;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create an array of PointF objects.
        PointF[] apf = {
            new PointF(27.8F, 32.62F),
            new PointF(99.3F, 147.273F),
            new PointF(7.5F, 1412.2F) };

        // Display each element in the PointF array.
        Console.WriteLine();
        foreach( PointF p in apf )
            Console.WriteLine(p);

        // Convert each PointF element to a Point object.
        Point[] ap = Array.ConvertAll(apf, 
            new Converter<PointF, Point>(PointFToPoint));

        // Display each element in the Point array.
        Console.WriteLine();
        foreach( Point p in ap )
        {
            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}
 */
Imports System.Drawing
Imports System.Collections.Generic

Public Class Example
    Public Shared Sub Main()
        ' Create an array of PointF objects.
        Dim apf() As PointF = { _
            New PointF(27.8, 32.62), _
            New PointF(99.3, 147.273), _
            New PointF(7.5, 1412.2)  }

        ' Display each element in the PointF array.
        Console.WriteLine()
        For Each p As PointF In apf
            Console.WriteLine(p)
        Next
        
        ' Convert each PointF element to a Point object.
        Dim ap() As Point = Array.ConvertAll(apf, _
            New Converter(Of PointF, Point)(AddressOf PointFToPoint))

        ' Display each element in the Point array.
        Console.WriteLine()
        For Each p As Point In ap
            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
' The 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}

示例 2Example 2

下面的代码示例定义了一个名PointFToPoint为的方法PointF , 该方法Point将结构转换为结构。The following code example defines a method named PointFToPoint that converts a PointF structure to a Point structure. 然后, 该示例创建List<T>PointF一个结构, 创建Converter\<PointF, Point>一个ConvertAll用于Converter(Of PointF, Point)表示PointFToPoint方法的委托 (在 Visual Basic 中), 并将委托传递给方法。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 method. 方法将输入列表的每个元素传递PointFToPoint给方法, 并将转换后的元素放入新的Point结构列表。 ConvertAllThe ConvertAll method passes each element of the input list to the PointFToPoint method and puts the converted elements into a new list of Point structures. 将显示这两个列表。Both lists are displayed.

#using <System.Drawing.dll>

using namespace System;
using namespace System::Drawing;
using namespace System::Collections::Generic;

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

void main()
{
    List<PointF>^ lpf = gcnew List<PointF>();

    lpf->Add(PointF(27.8F, 32.62F));
    lpf->Add(PointF(99.3F, 147.273F));
    lpf->Add(PointF(7.5F, 1412.2F));

    Console::WriteLine();
    for each(PointF p in lpf)
    {
        Console::WriteLine(p);
    }

    List<Point>^ lp = 
        lpf->ConvertAll<Point>(
            gcnew Converter<PointF, Point>(PointFToPoint)
        );

    Console::WriteLine();
    for each(Point p in lp)
    {
        Console::WriteLine(p);
    }
}

/* 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}
 */
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}
 */
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}

注解

该类的ConvertAll方法ArrayConvertAll类的方法使用此委托将集合的每个元素从一种类型转换为另一种类型。 List<T>This delegate is used by the ConvertAll method of the Array class and the ConvertAll method of the List<T> class to convert each element of the collection from one type to another.

扩展方法

GetMethodInfo(Delegate)

获取指示指定委托表示的方法的对象。Gets an object that represents the method represented by the specified delegate.

适用于