Comparison<T> 代理人
定義
重要
一部の情報は、リリース前に大きく変更される可能性があるプレリリースされた製品に関するものです。 Microsoft は、ここに記載されている情報について、明示または黙示を問わず、一切保証しません。
同じ型の 2 つのオブジェクトを比較するメソッドを表します。
generic <typename T>
public delegate int Comparison(T x, T y);public delegate int Comparison<in T>(T x, T y);public delegate int Comparison<in T>(T x, T y) where T : allows ref struct;public delegate int Comparison<T>(T x, T y);type Comparison<'T> = delegate of 'T * 'T -> intPublic Delegate Function Comparison(Of In T)(x As T, y As T) As Integer Public Delegate Function Comparison(Of T)(x As T, y As T) As Integer 型パラメーター
- T
比較するオブジェクトの型。
この型パラメーターは反変です。 つまり、指定した型、または弱い派生型のいずれかを使用することができます。 共変性および反変性の詳細については、「ジェネリックの共変性と反変性」をご覧ください。パラメーター
- x
- T
比較する最初のオブジェクト。
- y
- T
比較する 2 番目のオブジェクト。
戻り値
次の表に示すように、 x と yの相対値を示す符号付き整数。
| 価値 | 意味 |
|---|---|
| 0 未満 |
x が y未満です。
|
| 0 |
x は yと等しくなります。
|
| 0 より大きい |
x が y より大きい。
|
例
次のコード例では、Comparison<T> メソッドのオーバーロードでSort(Comparison<T>) デリゲートを使用する方法を示します。
このコード例では、 CompareDinosByLengthという名前の文字列の代替比較メソッドを定義します。 このメソッドは次のように機能します。まず、比較対象が nullでテストされ、null 参照が null 以外の値より小さいと見なされます。 次に、文字列の長さが比較され、長い文字列が大きいと見なされます。 3 番目に、長さが等しい場合は、通常の文字列比較が使用されます。
文字列の List<T> が作成され、特定の順序で 4 つの文字列が設定されます。 リストには、空の文字列と null 参照も含まれています。 リストが表示され、Comparison<T> メソッドを表すCompareDinosByLengthジェネリック デリゲートを使用して並べ替えられて、再び表示されます。
using System;
using System.Collections.Generic;
public class Example
{
private static int CompareDinosByLength(string x, string y)
{
if (x == null)
{
if (y == null)
{
// If x is null and y is null, they're
// equal.
return 0;
}
else
{
// If x is null and y is not null, y
// is greater.
return -1;
}
}
else
{
// If x is not null...
//
if (y == null)
// ...and y is null, x is greater.
{
return 1;
}
else
{
// ...and y is not null, compare the
// lengths of the two strings.
//
int retval = x.Length.CompareTo(y.Length);
if (retval != 0)
{
// If the strings are not of equal length,
// the longer string is greater.
//
return retval;
}
else
{
// If the strings are of equal length,
// sort them with ordinary string comparison.
//
return x.CompareTo(y);
}
}
}
}
public static void Main()
{
List<string> dinosaurs = new List<string>();
dinosaurs.Add("Pachycephalosaurus");
dinosaurs.Add("Amargasaurus");
dinosaurs.Add("");
dinosaurs.Add(null);
dinosaurs.Add("Mamenchisaurus");
dinosaurs.Add("Deinonychus");
Display(dinosaurs);
Console.WriteLine("\nSort with generic Comparison<string> delegate:");
dinosaurs.Sort(CompareDinosByLength);
Display(dinosaurs);
}
private static void Display(List<string> list)
{
Console.WriteLine();
foreach( string s in list )
{
if (s == null)
Console.WriteLine("(null)");
else
Console.WriteLine("\"{0}\"", s);
}
}
}
/* This code example produces the following output:
"Pachycephalosaurus"
"Amargasaurus"
""
(null)
"Mamenchisaurus"
"Deinonychus"
Sort with generic Comparison<string> delegate:
(null)
""
"Deinonychus"
"Amargasaurus"
"Mamenchisaurus"
"Pachycephalosaurus"
*/
open System
let compareDinosByLength (x: string) (y: string) =
match x with
| null when isNull y ->
// If x is null and y is null, they're equal.
0
| null ->
// If x is null and y is not null, y is greater.
-1
| _ when isNull y->
// If x is not null and y is null, x is greater.
1
| _ ->
// If x is not null and y is not null, compare the lengths of the two strings.
let retval = x.Length.CompareTo y.Length
if retval <> 0 then
// If the strings are not of equal length, the longer string is greater.
retval
else
// If the strings are of equal length, sort them with ordinary string comparison.
x.CompareTo y
let display list =
printfn ""
for s in list do
if isNull s then
printfn "(null)"
else
printfn $"\"%s{s}\""
let dinosaurs = ResizeArray()
dinosaurs.Add "Pachycephalosaurus"
dinosaurs.Add "Amargasaurus"
dinosaurs.Add ""
dinosaurs.Add null
dinosaurs.Add "Mamenchisaurus"
dinosaurs.Add "Deinonychus"
display dinosaurs
printfn "\nSort with generic Comparison<string> delegate:"
dinosaurs.Sort compareDinosByLength
display dinosaurs
// This code example produces the following output:
//
// "Pachycephalosaurus"
// "Amargasaurus"
// ""
// (null)
// "Mamenchisaurus"
// "Deinonychus"
//
// Sort with generic Comparison<string> delegate:
//
// (null)
// ""
// "Deinonychus"
// "Amargasaurus"
// "Mamenchisaurus"
// "Pachycephalosaurus"
Imports System.Collections.Generic
Public Class Example
Private Shared Function CompareDinosByLength( _
ByVal x As String, ByVal y As String) As Integer
If x Is Nothing Then
If y Is Nothing Then
' If x is Nothing and y is Nothing, they're
' equal.
Return 0
Else
' If x is Nothing and y is not Nothing, y
' is greater.
Return -1
End If
Else
' If x is not Nothing...
'
If y Is Nothing Then
' ...and y is Nothing, x is greater.
Return 1
Else
' ...and y is not Nothing, compare the
' lengths of the two strings.
'
Dim retval As Integer = _
x.Length.CompareTo(y.Length)
If retval <> 0 Then
' If the strings are not of equal length,
' the longer string is greater.
'
Return retval
Else
' If the strings are of equal length,
' sort them with ordinary string comparison.
'
Return x.CompareTo(y)
End If
End If
End If
End Function
Public Shared Sub Main()
Dim dinosaurs As New List(Of String)
dinosaurs.Add("Pachycephalosaurus")
dinosaurs.Add("Amargasaurus")
dinosaurs.Add("")
dinosaurs.Add(Nothing)
dinosaurs.Add("Mamenchisaurus")
dinosaurs.Add("Deinonychus")
Display(dinosaurs)
Console.WriteLine(vbLf & "Sort with generic Comparison(Of String) delegate:")
dinosaurs.Sort(AddressOf CompareDinosByLength)
Display(dinosaurs)
End Sub
Private Shared Sub Display(ByVal lis As List(Of String))
Console.WriteLine()
For Each s As String In lis
If s Is Nothing Then
Console.WriteLine("(Nothing)")
Else
Console.WriteLine("""{0}""", s)
End If
Next
End Sub
End Class
' This code example produces the following output:
'
'"Pachycephalosaurus"
'"Amargasaurus"
'""
'(Nothing)
'"Mamenchisaurus"
'"Deinonychus"
'
'Sort with generic Comparison(Of String) delegate:
'
'(Nothing)
'""
'"Deinonychus"
'"Amargasaurus"
'"Mamenchisaurus"
'"Pachycephalosaurus"
次の例では、 Comparison<T> デリゲートを使用して、 CityInfo オブジェクトのコレクションの要素を並べ替えます。
CityInfo は、市区町村とその人口に関する情報を含むアプリケーション定義クラスです。 この例では、CompareByName オブジェクトを並べ替える 3 つの異なる方法を提供する 3 つのメソッド (CompareByPopulation、CompareByNames、CityInfo) を定義します。 各メソッドは、comparison メソッドのArray.Sort<T>(T[], Comparison<T>)引数に割り当てられます。
using System;
public class CityInfo
{
string cityName;
string countryName;
int pop2010;
public CityInfo(string name, string country, int pop2010)
{
this.cityName = name;
this.countryName = country;
this.pop2010 = pop2010;
}
public string City
{ get { return this.cityName; } }
public string Country
{ get { return this.countryName; } }
public int Population
{ get { return this.pop2010; } }
public static int CompareByName(CityInfo city1, CityInfo city2)
{
return String.Compare(city1.City, city2.City);
}
public static int CompareByPopulation(CityInfo city1, CityInfo city2)
{
return city1.Population.CompareTo(city2.Population);
}
public static int CompareByNames(CityInfo city1, CityInfo city2)
{
return String.Compare(city1.Country + city1.City, city2.Country + city2.City);
}
}
public class Example
{
public static void Main()
{
CityInfo NYC = new CityInfo("New York City", "United States of America", 8175133 );
CityInfo Det = new CityInfo("Detroit", "United States of America", 713777);
CityInfo Paris = new CityInfo("Paris", "France", 2193031);
CityInfo[] cities = { NYC, Det, Paris };
// Display ordered array.
DisplayArray(cities);
// Sort array by city name.
Array.Sort(cities, CityInfo.CompareByName);
DisplayArray(cities);
// Sort array by population.
Array.Sort(cities, CityInfo.CompareByPopulation);
DisplayArray(cities);
// Sort array by country + city name.
Array.Sort(cities, CityInfo.CompareByNames);
DisplayArray(cities);
}
private static void DisplayArray(CityInfo[] cities)
{
Console.WriteLine("{0,-20} {1,-25} {2,10}", "City", "Country", "Population");
foreach (var city in cities)
Console.WriteLine("{0,-20} {1,-25} {2,10:N0}", city.City,
city.Country, city.Population);
Console.WriteLine();
}
}
// The example displays the following output:
// City Country Population
// New York City United States of America 8,175,133
// Detroit United States of America 713,777
// Paris France 2,193,031
//
// City Country Population
// Detroit United States of America 713,777
// New York City United States of America 8,175,133
// Paris France 2,193,031
//
// City Country Population
// Detroit United States of America 713,777
// Paris France 2,193,031
// New York City United States of America 8,175,133
//
// City Country Population
// Paris France 2,193,031
// Detroit United States of America 713,777
// New York City United States of America 8,175,133
open System
type CityInfo =
{ City: string
Country: string
Population: int }
static member CompareByName city1 city2 =
String.Compare(city1.City, city2.City)
static member CompareByPopulation city1 city2 =
city1.Population.CompareTo city2.Population
static member CompareByNames city1 city2 =
String.Compare(city1.Country + city1.City, city2.Country + city2.City)
let display cities =
printfn $"""{"City",-20} {"Country",-25} {"Population",10}"""
for city in cities do
printfn $"{city.City,-20} {city.Country,-25} {city.Population,10:N0}"
printfn ""
let NYC = { City = "New York City"; Country = "United States of America"; Population = 8175133 }
let Det = { City = "Detroit"; Country = "United States of America"; Population = 713777 }
let Paris = { City = "Paris"; Country = "France"; Population = 2193031 }
let cities = [| NYC; Det; Paris |]
// Display ordered array.
display cities
// Sort array by city name.
Array.Sort(cities, CityInfo.CompareByName)
display cities
// Sort array by population.
Array.Sort(cities, CityInfo.CompareByPopulation);
display cities
// Sort array by country + city name.
Array.Sort(cities, CityInfo.CompareByNames);
display cities
// The example displays the following output:
// City Country Population
// New York City United States of America 8,175,133
// Detroit United States of America 713,777
// Paris France 2,193,031
//
// City Country Population
// Detroit United States of America 713,777
// New York City United States of America 8,175,133
// Paris France 2,193,031
//
// City Country Population
// Detroit United States of America 713,777
// Paris France 2,193,031
// New York City United States of America 8,175,133
//
// City Country Population
// Paris France 2,193,031
// Detroit United States of America 713,777
// New York City United States of America 8,175,133
Public Class CityInfo
Dim cityName As String
Dim countryName As String
Dim pop2010 As Integer
Public Sub New(name As String, country As String, pop2010 As Integer)
Me.cityName = name
Me.countryName = country
Me.pop2010 = pop2010
End Sub
Public ReadOnly Property City As String
Get
Return Me.cityName
End Get
End Property
Public ReadOnly Property Country As String
Get
Return Me.countryName
End Get
End Property
Public ReadOnly Property Population As Integer
Get
Return Me.pop2010
End Get
End Property
Public Shared Function CompareByName(city1 As CityInfo, city2 As CityInfo) As Integer
Return String.Compare(city1.City, city2.City)
End Function
Public Shared Function CompareByPopulation(city1 As CityInfo, city2 As CityInfo) As Integer
Return city1.Population.CompareTo(city2.Population)
End Function
Public Shared Function CompareByNames(city1 As CityInfo, city2 As CityInfo) As Integer
Return String.Compare(city1.Country + city1.City, city2.Country + city2.City)
End Function
End Class
Module Example
Public Sub Main()
Dim NYC As New CityInfo("New York City", "United States of America", 8175133)
Dim Det As New CityInfo("Detroit", "United States of America", 713777)
Dim Paris As New CityInfo("Paris", "France", 2193031)
Dim cities As CityInfo() = { NYC, Det, Paris }
' Display ordered array.
DisplayArray(cities)
' Sort array by city name.
Array.Sort(cities, AddressOf CityInfo.CompareByName)
DisplayArray(cities)
' Sort array by population.
Array.Sort(cities, AddressOf CityInfo.CompareByPopulation)
DisplayArray(cities)
' Sort array by country + city name.
Array.Sort(cities, AddressOf CityInfo.CompareByNames)
DisplayArray(cities)
End Sub
Private Sub DisplayArray(cities() As CityInfo)
Console.WriteLine("{0,-20} {1,-25} {2,10}", "City", "Country/Region", "Population")
For Each city In cities
Console.WriteLine("{0,-20} {1,-25} {2,10:N0}", city.City, city.Country, city.Population)
Next
Console.WriteLine()
End Sub
End Module
' The example displays the following output:
' City Country/Region Population
' New York City United States of America 8,175,133
' Detroit United States of America 713,777
' Paris France 2,193,031
'
' City Country/Region Population
' Detroit United States of America 713,777
' New York City United States of America 8,175,133
' Paris France 2,193,031
'
' City Country/Region Population
' Detroit United States of America 713,777
' Paris France 2,193,031
' New York City United States of America 8,175,133
'
' City Country/Region Population
' Paris France 2,193,031
' Detroit United States of America 713,777
' New York City United States of America 8,175,133
注釈
このデリゲートは、配列またはリストの要素を並べ替えるために、Sort<T>(T[], Comparison<T>) クラスのArray メソッド オーバーロードとSort(Comparison<T>) クラスのList<T> メソッド オーバーロードによって使用されます。
拡張メソッド
| 名前 | 説明 |
|---|---|
| GetMethodInfo(Delegate) |
指定したデリゲートによって表されるメソッドを表すオブジェクトを取得します。 |
