IComparable Interface
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Defines a generalized type-specific comparison method that a value type or class implements to order or sort its instances.
public interface class IComparable
public interface IComparable
[System.Runtime.InteropServices.ComVisible(true)]
public interface IComparable
type IComparable = interface
[<System.Runtime.InteropServices.ComVisible(true)>]
type IComparable = interface
Public Interface IComparable
- Derived
- Attributes
The following example illustrates the implementation of IComparable and the requisite CompareTo method.
using namespace System;
using namespace System::Collections;
public ref class Temperature: public IComparable {
/// <summary>
/// IComparable.CompareTo implementation.
/// </summary>
protected:
// The value holder
Double m_value;
public:
virtual Int32 CompareTo( Object^ obj ) {
if (obj == nullptr) return 1;
if ( obj->GetType() == Temperature::typeid ) {
Temperature^ temp = dynamic_cast<Temperature^>(obj);
return m_value.CompareTo( temp->m_value );
}
throw gcnew ArgumentException( "object is not a Temperature" );
}
property Double Value {
Double get() {
return m_value;
}
void set( Double value ) {
m_value = value;
}
}
property Double Celsius {
Double get() {
return (m_value - 32) / 1.8;
}
void set( Double value ) {
m_value = (value * 1.8) + 32;
}
}
};
int main()
{
ArrayList^ temperatures = gcnew ArrayList;
// Initialize random number generator.
Random^ rnd = gcnew Random;
// Generate 10 temperatures between 0 and 100 randomly.
for (int ctr = 1; ctr <= 10; ctr++)
{
int degrees = rnd->Next(0, 100);
Temperature^ temp = gcnew Temperature;
temp->Value = degrees;
temperatures->Add(temp);
}
// Sort ArrayList.
temperatures->Sort();
for each (Temperature^ temp in temperatures)
Console::WriteLine(temp->Value);
return 0;
}
// The example displays the following output to the console (individual
// values may vary because they are randomly generated):
// 2
// 7
// 16
// 17
// 31
// 37
// 58
// 66
// 72
// 95
using System;
using System.Collections;
public class Temperature : IComparable
{
// The temperature value
protected double temperatureF;
public int CompareTo(object obj) {
if (obj == null) return 1;
Temperature otherTemperature = obj as Temperature;
if (otherTemperature != null)
return this.temperatureF.CompareTo(otherTemperature.temperatureF);
else
throw new ArgumentException("Object is not a Temperature");
}
public double Fahrenheit
{
get
{
return this.temperatureF;
}
set
{
this.temperatureF = value;
}
}
public double Celsius
{
get
{
return (this.temperatureF - 32) * (5.0/9);
}
set
{
this.temperatureF = (value * 9.0/5) + 32;
}
}
}
public class CompareTemperatures
{
public static void Main()
{
ArrayList temperatures = new ArrayList();
// Initialize random number generator.
Random rnd = new Random();
// Generate 10 temperatures between 0 and 100 randomly.
for (int ctr = 1; ctr <= 10; ctr++)
{
int degrees = rnd.Next(0, 100);
Temperature temp = new Temperature();
temp.Fahrenheit = degrees;
temperatures.Add(temp);
}
// Sort ArrayList.
temperatures.Sort();
foreach (Temperature temp in temperatures)
Console.WriteLine(temp.Fahrenheit);
}
}
// The example displays the following output to the console (individual
// values may vary because they are randomly generated):
// 2
// 7
// 16
// 17
// 31
// 37
// 58
// 66
// 72
// 95
open System
open System.Collections
type Temperature() =
// The temperature value
let mutable temperatureF = 0.
interface IComparable with
member _.CompareTo(obj) =
match obj with
| null -> 1
| :? Temperature as other ->
temperatureF.CompareTo other.Fahrenheit
| _ ->
invalidArg (nameof obj) "Object is not a Temperature"
member _.Fahrenheit
with get () =
temperatureF
and set (value) =
temperatureF <- value
member _.Celsius
with get () =
(temperatureF - 32.) * (5. / 9.)
and set (value) =
temperatureF <- (value * 9. / 5.) + 32.
let temperatures = ResizeArray()
// Initialize random number generator.
let rnd = Random()
// Generate 10 temperatures between 0 and 100 randomly.
for _ = 1 to 10 do
let degrees = rnd.Next(0, 100)
let temp = Temperature(Fahrenheit=degrees)
temperatures.Add temp
// Sort ResizeArray.
temperatures.Sort()
for temp in temperatures do
printfn $"{temp.Fahrenheit}"
// The example displays the following output to the console (individual
// values may vary because they are randomly generated):
// 2
// 7
// 16
// 17
// 31
// 37
// 58
// 66
// 72
// 95
Imports System.Collections
Public Class Temperature
Implements IComparable
' The temperature value
Protected temperatureF As Double
Public Overloads Function CompareTo(ByVal obj As Object) As Integer _
Implements IComparable.CompareTo
If obj Is Nothing Then Return 1
Dim otherTemperature As Temperature = TryCast(obj, Temperature)
If otherTemperature IsNot Nothing Then
Return Me.temperatureF.CompareTo(otherTemperature.temperatureF)
Else
Throw New ArgumentException("Object is not a Temperature")
End If
End Function
Public Property Fahrenheit() As Double
Get
Return temperatureF
End Get
Set(ByVal Value As Double)
Me.temperatureF = Value
End Set
End Property
Public Property Celsius() As Double
Get
Return (temperatureF - 32) * (5/9)
End Get
Set(ByVal Value As Double)
Me.temperatureF = (Value * 9/5) + 32
End Set
End Property
End Class
Public Module CompareTemperatures
Public Sub Main()
Dim temperatures As New ArrayList
' Initialize random number generator.
Dim rnd As New Random()
' Generate 10 temperatures between 0 and 100 randomly.
For ctr As Integer = 1 To 10
Dim degrees As Integer = rnd.Next(0, 100)
Dim temp As New Temperature
temp.Fahrenheit = degrees
temperatures.Add(temp)
Next
' Sort ArrayList.
temperatures.Sort()
For Each temp As Temperature In temperatures
Console.WriteLine(temp.Fahrenheit)
Next
End Sub
End Module
' The example displays the following output to the console (individual
' values may vary because they are randomly generated):
' 2
' 7
' 16
' 17
' 31
' 37
' 58
' 66
' 72
' 95
This interface is implemented by types whose values can be ordered or sorted. It requires that implementing types define a single method, CompareTo(Object), that indicates whether the position of the current instance in the sort order is before, after, or the same as a second object of the same type. The instance's IComparable implementation is called automatically by methods such as Array.Sort and ArrayList.Sort.
The implementation of the CompareTo(Object) method must return an Int32 that has one of three values, as shown in the following table.
Value | Meaning |
---|---|
Less than zero | The current instance precedes the object specified by the CompareTo method in the sort order. |
Zero | This current instance occurs in the same position in the sort order as the object specified by the CompareTo method. |
Greater than zero | This current instance follows the object specified by the CompareTo method in the sort order. |
All numeric types (such as Int32 and Double) implement IComparable, as do String, Char, and DateTime. Custom types should also provide their own implementation of IComparable to enable object instances to be ordered or sorted.
Compare |
Compares the current instance with another object of the same type and returns an integer that indicates whether the current instance precedes, follows, or occurs in the same position in the sort order as the other object. |
Produkt | Versionen |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1 |
UWP | 10.0 |
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