# IComparable<T>.CompareTo(T) メソッド

## 定義

``````public:
int CompareTo(T other);``````
``public int CompareTo (T other);``
``abstract member CompareTo : 'T -> int``
``Public Function CompareTo (other As T) As Integer``

#### パラメーター

other
T

このインスタンスと比較するオブジェクト。An object to compare with this instance.

#### 戻り値

Int32

[値]Value 説明Meaning
0 より小さい値Less than zero このインスタンスの位置が、並べ替え順序において `other` よりも前です。This instance precedes `other` in the sort order.
0Zero 並べ替え順序における、このインスタンスと `other` の位置が同じです。This instance occurs in the same position in the sort order as `other`.
0 より大きい値Greater than zero このインスタンスの位置が、並べ替え順序において `other` よりも後ろです。This instance follows `other` in the sort order.

## 例

``````#using <System.dll>

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

public ref class Temperature: public IComparable<Temperature^> {

protected:
// The underlying temperature value.
Double m_value;

public:
// Implement the generic CompareTo method with the Temperature class
// as the Type parameter.
virtual Int32 CompareTo( Temperature^ other ) {

// If other is not a valid object reference, this instance
// is greater.
if (other == nullptr) return 1;

// The temperature comparison depends on the comparison of the
// the underlying Double values.
return m_value.CompareTo( other->m_value );
}

// Define the is greater than operator.
bool operator>=  (Temperature^ other)
{
return CompareTo(other) == 1;
}

// Define the is less than operator.
bool operator<  (Temperature^ other)
{
return CompareTo(other) == -1;
}

// Define the is greater than or equal to operator.
bool operator>  (Temperature^ other)
{
return CompareTo(other) >= 0;
}

// Define the is less than or equal to operator.
bool operator<=  (Temperature^ other)
{
return CompareTo(other) <= 0;
}

property Double Celsius {
Double get() {
return m_value + 273.15;
}
}

property Double Kelvin {
Double get() {
return m_value;
}
void set( Double value ) {
if (value < 0)
throw gcnew ArgumentException("Temperature cannot be less than absolute zero.");
else
m_value = value;
}
}

Temperature(Double kelvins) {
this->Kelvin = kelvins;
}
};

int main() {
SortedList<Temperature^, String^>^ temps =
gcnew SortedList<Temperature^, String^>();

// Add entries to the sorted list, out of order.
temps->Add(gcnew Temperature(0), "Absolute zero");
temps->Add(gcnew Temperature(273.15), "Freezing point of water");
temps->Add(gcnew Temperature(5100.15), "Boiling point of Carbon");
temps->Add(gcnew Temperature(373.15), "Boiling point of water");

for each( KeyValuePair<Temperature^, String^>^ kvp in temps )
{
Console::WriteLine("{0} is {1} degrees Celsius.", kvp->Value, kvp->Key->Celsius);
}
}
/* The example displays the following output:
Absolute zero is 273.15 degrees Celsius.
Freezing point of water is 546.3 degrees Celsius.
Boiling point of water is 646.3 degrees Celsius.
Melting point of Lead is 873.8 degrees Celsius.
Boiling point of Lead is 2290.3 degrees Celsius.
Boiling point of Carbon is 5373.3 degrees Celsius.
*/
``````
``````using System;
using System.Collections.Generic;

public class Temperature : IComparable<Temperature>
{
// Implement the generic CompareTo method with the Temperature
// class as the Type parameter.
//
public int CompareTo(Temperature other)
{
// If other is not a valid object reference, this instance is greater.
if (other == null) return 1;

// The temperature comparison depends on the comparison of
// the underlying Double values.
return m_value.CompareTo(other.m_value);
}

// Define the is greater than operator.
public static bool operator >  (Temperature operand1, Temperature operand2)
{
return operand1.CompareTo(operand2) == 1;
}

// Define the is less than operator.
public static bool operator <  (Temperature operand1, Temperature operand2)
{
return operand1.CompareTo(operand2) == -1;
}

// Define the is greater than or equal to operator.
public static bool operator >=  (Temperature operand1, Temperature operand2)
{
return operand1.CompareTo(operand2) >= 0;
}

// Define the is less than or equal to operator.
public static bool operator <=  (Temperature operand1, Temperature operand2)
{
return operand1.CompareTo(operand2) <= 0;
}

// The underlying temperature value.
protected double m_value = 0.0;

public double Celsius
{
get
{
return m_value - 273.15;
}
}

public double Kelvin
{
get
{
return m_value;
}
set
{
if (value < 0.0)
{
throw new ArgumentException("Temperature cannot be less than absolute zero.");
}
else
{
m_value = value;
}
}
}

public Temperature(double kelvins)
{
this.Kelvin = kelvins;
}
}

public class Example
{
public static void Main()
{
SortedList<Temperature, string> temps =
new SortedList<Temperature, string>();

// Add entries to the sorted list, out of order.
temps.Add(new Temperature(0), "Absolute zero");
temps.Add(new Temperature(273.15), "Freezing point of water");
temps.Add(new Temperature(5100.15), "Boiling point of Carbon");
temps.Add(new Temperature(373.15), "Boiling point of water");

foreach( KeyValuePair<Temperature, string> kvp in temps )
{
Console.WriteLine("{0} is {1} degrees Celsius.", kvp.Value, kvp.Key.Celsius);
}
}
}
/* This example displays the following output:
Absolute zero is -273.15 degrees Celsius.
Freezing point of water is 0 degrees Celsius.
Boiling point of water is 100 degrees Celsius.
Melting point of Lead is 327.5 degrees Celsius.
Boiling point of Lead is 1744 degrees Celsius.
Boiling point of Carbon is 4827 degrees Celsius.
*/
``````
``````Imports System.Collections.Generic

Public Class Temperature
Implements IComparable(Of Temperature)

' Implement the generic CompareTo method with the Temperature class
' as the type parameter.
'
Public Overloads Function CompareTo(ByVal other As Temperature) As Integer _
Implements IComparable(Of Temperature).CompareTo

' If other is not a valid object reference, this instance is greater.
If other Is Nothing Then Return 1

' The temperature comparison depends on the comparison of the
' the underlying Double values.
Return m_value.CompareTo(other.m_value)
End Function

' Define the is greater than operator.
Public Shared Operator >  (operand1 As Temperature, operand2 As Temperature) As Boolean
Return operand1.CompareTo(operand2) = 1
End Operator

' Define the is less than operator.
Public Shared Operator <  (operand1 As Temperature, operand2 As Temperature) As Boolean
Return operand1.CompareTo(operand2) = -1
End Operator

' Define the is greater than or equal to operator.
Public Shared Operator >=  (operand1 As Temperature, operand2 As Temperature) As Boolean
Return operand1.CompareTo(operand2) >= 0
End Operator

' Define the is less than operator.
Public Shared Operator <=  (operand1 As Temperature, operand2 As Temperature) As Boolean
Return operand1.CompareTo(operand2) <= 0
End Operator

' The underlying temperature value.
Protected m_value As Double = 0.0

Public ReadOnly Property Celsius() As Double
Get
Return m_value - 273.15
End Get
End Property

Public Property Kelvin() As Double
Get
Return m_value
End Get
Set(ByVal Value As Double)
If value < 0.0 Then
Throw New ArgumentException("Temperature cannot be less than absolute zero.")
Else
m_value = Value
End If
End Set
End Property

Public Sub New(ByVal kelvins As Double)
Me.Kelvin = kelvins
End Sub
End Class

Public Class Example
Public Shared Sub Main()
Dim temps As New SortedList(Of Temperature, String)

' Add entries to the sorted list, out of order.
temps.Add(New Temperature(0), "Absolute zero")
temps.Add(New Temperature(273.15), "Freezing point of water")
temps.Add(New Temperature(5100.15), "Boiling point of Carbon")
temps.Add(New Temperature(373.15), "Boiling point of water")

For Each kvp As KeyValuePair(Of Temperature, String) In temps
Console.WriteLine("{0} is {1} degrees Celsius.", kvp.Value, kvp.Key.Celsius)
Next
End Sub
End Class

' The example displays the following output:
'      Absolute zero is -273.15 degrees Celsius.
'      Freezing point of water is 0 degrees Celsius.
'      Boiling point of water is 100 degrees Celsius.
'      Melting point of Lead is 327.5 degrees Celsius.
'      Boiling point of Lead is 1744 degrees Celsius.
'      Boiling point of Carbon is 4827 degrees Celsius.
'
``````

## 注釈

CompareTo ジェネリックコレクションオブジェクトのメンバーを並べ替えるための厳密に型指定された比較メソッドを提供します。CompareTo provides a strongly typed comparison method for ordering members of a generic collection object. このため、通常、開発者コードから直接呼び出されることはありません。Because of this, it is usually not called directly from developer code. 代わりに、やなどのメソッドによって自動的に呼び出され List<T>.Sort() Add ます。Instead, it is called automatically by methods such as List<T>.Sort() and Add.

このメソッドは単なる定義であり、有効にするために特定のクラスまたは値型によって実装される必要があります。This method is only a definition and must be implemented by a specific class or value type to have effect. [戻り値] セクションで指定された比較の意味 ("前"、"前"、"の位置は"、および "は" になります) は、特定の実装によって異なります。The meaning of the comparisons specified in the Return Values section ("precedes", "occurs in the same position as", and "follows) depends on the particular implementation.

## 注意 (実装者)

オブジェクト A、B、および C の場合、次の条件を満たす必要があります。For objects A, B, and C, the following must be true: 0を返すには`、CompareTo (a)`が必要です。`A.CompareTo(A)` is required to return zero.

`Compareto (B)`が0を返した場合は、0を返すためには`、b. compareto (A)`が必要です。If `A.CompareTo(B)` returns zero, then `B.CompareTo(A)` is required to return zero.

`Compareto (B)`が0と b を返した場合、 `compareto (c)`は0を返し、0を返すには`compareto (c)`が必要です。If `A.CompareTo(B)` returns zero and `B.CompareTo(C)` returns zero, then `A.CompareTo(C)` is required to return zero.

`Compareto (B)`が0以外の値を返す場合、逆の符号の値を返すには`、b. compareto (A)`が必要です。If `A.CompareTo(B)` returns a value other than zero, then `B.CompareTo(A)` is required to return a value of the opposite sign.

`Compareto (b)`が0以外の値を返し、 `x` `b-tree (c)`がと同じ符号の値を返す場合は、 `y` `x` として同じ符号の値を返すために`、compareto (c` ) が必要 `x` `y` になります。If `A.CompareTo(B)` returns a value `x` that is not equal to zero, and `B.CompareTo(C)` returns a value `y` of the same sign as `x`, then `A.CompareTo(C)` is required to return a value of the same sign as `x` and `y`.

## 注意 (呼び出し元)

CompareTo(T)クラスのインスタンスの順序を決定するには、メソッドを使用します。Use the CompareTo(T) method to determine the ordering of instances of a class.