IComparable<T> 接口
定义
重要
一些信息与预发行产品相关,相应产品在发行之前可能会进行重大修改。 对于此处提供的信息,Microsoft 不作任何明示或暗示的担保。
定义由值类型或类实现的通用比较方法,旨在创建特定于类型的比较方法以对实例进行排序。
generic <typename T>
public interface class IComparable
public interface IComparable<in T>
public interface IComparable<T>
type IComparable<'T> = interface
Public Interface IComparable(Of In T)
Public Interface IComparable(Of T)
类型参数
- 派生
示例
以下示例演示了简单 Temperature
对象的 实现IComparable<T>。 该示例使用对象键创建字符串 SortedList<TKey,TValue> 集合 Temperature
,并按顺序向列表中添加几对温度和字符串。 在调用 Add 方法时, SortedList<TKey,TValue> 集合使用 IComparable<T> 实现对列表条目进行排序,然后按温度上升的顺序显示这些条目。
#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) >= 0;
}
// Define the is less than operator.
bool operator< (Temperature^ other)
{
return CompareTo(other) < 0;
}
// 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(2017.15), "Boiling point of Lead");
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");
temps->Add(gcnew Temperature(600.65), "Melting point of Lead");
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) > 0;
}
// Define the is less than operator.
public static bool operator < (Temperature operand1, Temperature operand2)
{
return operand1.CompareTo(operand2) < 0;
}
// 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(2017.15), "Boiling point of Lead");
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");
temps.Add(new Temperature(600.65), "Melting point of Lead");
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.
*/
open System
open System.Collections.Generic
type Temperature(kelvins: double) =
// The underlying temperature value.
let mutable kelvins = kelvins
do
if kelvins < 0. then
invalidArg (nameof kelvins) "Temperature cannot be less than absolute zero."
// Define the is greater than operator.
static member op_GreaterThan (operand1: Temperature, operand2: Temperature) =
operand1.CompareTo operand2 > 0
// Define the is less than operator.
static member op_LessThan (operand1: Temperature, operand2: Temperature) =
operand1.CompareTo operand2 < 0
// Define the is greater than or equal to operator.
static member op_GreaterThanOrEqual (operand1: Temperature, operand2: Temperature) =
operand1.CompareTo operand2 >= 0
// Define the is less than or equal to operator.
static member op_LessThanOrEqual (operand1: Temperature, operand2: Temperature) =
operand1.CompareTo operand2 <= 0
member _.Celsius =
kelvins - 273.15
member _.Kelvin
with get () =
kelvins
and set (value) =
if value < 0. then
invalidArg (nameof value) "Temperature cannot be less than absolute zero."
else
kelvins <- value
// Implement the generic CompareTo method with the Temperature
// class as the Type parameter.
member _.CompareTo(other: Temperature) =
// If other is not a valid object reference, this instance is greater.
match box other with
| null -> 1
| _ ->
// The temperature comparison depends on the comparison of
// the underlying Double values.
kelvins.CompareTo(other.Kelvin)
interface IComparable<Temperature> with
member this.CompareTo(other) = this.CompareTo other
let temps = SortedList()
// Add entries to the sorted list, out of order.
temps.Add(Temperature 2017.15, "Boiling point of Lead")
temps.Add(Temperature 0., "Absolute zero")
temps.Add(Temperature 273.15, "Freezing point of water")
temps.Add(Temperature 5100.15, "Boiling point of Carbon")
temps.Add(Temperature 373.15, "Boiling point of water")
temps.Add(Temperature 600.65, "Melting point of Lead")
for kvp in temps do
printfn $"{kvp.Value} is {kvp.Key.Celsius} degrees 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) > 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
' 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(2017.15), "Boiling point of Lead")
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")
temps.Add(New Temperature(600.65), "Melting point of Lead")
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.
'
注解
此接口由值可以排序或排序的类型实现,并提供强类型比较方法,用于对泛型集合对象的成员进行排序。 例如,一个数字可以大于第二个数字,一个字符串可以按字母顺序显示在另一个字符串之前。 它要求实现类型定义一个 方法 , CompareTo(T)该方法指示当前实例在排序顺序中的位置是之前、之后还是与同一类型的第二个对象相同。 通常,不会直接从开发人员代码调用 方法。 相反,它由 和 Add等List<T>.Sort()方法自动调用。
通常,提供 IComparable<T> 实现的类型也会实现 IEquatable<T> 接口。 接口 IEquatable<T> 定义 Equals 方法,该方法确定实现类型的实例的相等性。
方法的 CompareTo(T) 实现必须返回具有三个 Int32 值之一的 ,如下表所示。
“值” | 含义 |
---|---|
小于零 | 此对象在排序顺序中由 CompareTo 方法指定的 对象之前。 |
零 | 此当前实例在排序顺序中与方法参数指定的 CompareTo 对象位于同一位置。 |
大于零 | 此当前实例遵循排序顺序中方法参数指定的 CompareTo 对象。 |
所有数值类型 ((如 Int32 和 Double) )String实现 IComparable<T>、、Char、 和 DateTime。 自定义类型还应提供其自己的 实现, IComparable<T> 以便对对象实例进行排序或排序。
实施者说明
将 接口的类型 IComparable<T> 参数替换为实现此接口的类型。
如果实现 IComparable<T>,则应重载 op_GreaterThan
、 op_GreaterThanOrEqual
、 op_LessThan
和 op_LessThanOrEqual
运算符,以返回与 CompareTo(T)一致的值。 此外,还应实现 IEquatable<T>。 有关完整信息, IEquatable<T> 请参阅文章。
方法
CompareTo(T) |
将当前实例与同一类型的另一个对象进行比较,并返回一个整数,该整数指示当前实例在排序顺序中的位置是位于另一个对象之前、之后还是与其位置相同。 |