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实现比较器接口IComparable<T>，让自定义类型数组也能排序
using System;namespace LinqDemo1{ class Program { static void Main(string[] args) { Person[] persons = { new Person {FirstName = "Damon", LastName = "Hill"}, new Person {FirstName = "Niki", LastName = "Lauda"}, new Person {FirstName = "Ayrton", LastName = "Senna"} }; Array.Sort(persons);//现在可以比较了 foreach (var p in persons) { Console.WriteLine(p); } Console.ReadKey(); } } class Person : IComparable<Person> { public int CompareTo(Person other) { if (other == null) { return 1; } int result = string.Compare(this.LastName, other.LastName); if (result == 0) { result = string.Compare(this.FirstName, other.FirstName); } return result; } public override string ToString() { return string.Format("{0} {1}", FirstName, LastName); } public string FirstName { get; set; } public string LastName { get; set; } }}
但有时候Person类是别人的类，无法修改，那怎么办呢？
在这种情况下，就可以定义一个新类，如：PersonComparer继承IComparer<Person>
using System;using System.Collections;using System.Collections.Generic;namespace LinqDemo1{ class Program { static void Main(string[] args) { Person[] persons = { new Person {FirstName = "Damon", LastName = "Hill"}, new Person {FirstName = "Niki", LastName = "Lauda"}, new Person {FirstName = "Ayrton", LastName = "Senna"} }; Array.Sort(persons, new PersonComparer(PersonCompareType.FirstName)); foreach (var p in persons) { Console.WriteLine(p); } Console.ReadKey(); } } public enum PersonCompareType { FirstName, LastName } public class PersonComparer : IComparer<Person> { private PersonCompareType compareType; public PersonComparer(PersonCompareType compareType) { this.compareType = compareType; } public int Compare(Person x, Person y) { if (x == null && y == null) return 0; if (x == null) return 1; if (y == null) return -1; switch (compareType) { case PersonCompareType.FirstName: return string.Compare(x.FirstName, y.FirstName); case PersonCompareType.LastName: return string.Compare(x.LastName, y.LastName); default: throw new ArgumentException("unexpected compare type"); } } } public class Person { public override string ToString() { return string.Format("{0} {1}", FirstName, LastName); } public string FirstName { get; set; } public string LastName { get; set; } }}
Array 类还提供了Sort()多个重载方法，它需要将一个委托作为参数，这个参数可以传递给方法，从而比较2个对象，而不需要依赖IComparable或IComparer接口，也就是说上面都白折腾了，有更高级的做法！那就是委托！
实现比较器接口IComparable<T>，让自定义类型数组也能排序
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