IComparable Interface
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Defines a generalized type-specific comparison method that a value type or class implements to order or sort its instances.
Assembly: mscorlib (in mscorlib.dll)
The IComparable type exposes the following members.
This interface is implemented by types whose values can be ordered or sorted. It requires that implementing types define a single method, CompareTo, 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.
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 allow object instances to be ordered or sorted.
The following code sample illustrates the implementation of IComparable and the requisite CompareTo method.
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 Example { public static void Demo(System.Windows.Controls.TextBlock outputBlock) { Temperature[] temperatures = new Temperature[10]; // 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[ctr - 1] = temp; } // Sort ArrayList. Array.Sort(temperatures); foreach (Temperature temp in temperatures) outputBlock.Text += temp.Fahrenheit + "\n"; } } // The example displays the following output (individual // values may vary because they are randomly generated): // 2 // 7 // 16 // 17 // 31 // 37 // 58 // 66 // 72 // 95
