示例

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class Employee3
{
    public string id;
    public string firstName;
    public string lastName;
    public static ArrayList GetEmployeesArrayList()
    {
        ArrayList al = new ArrayList();
        al.Add(new Employee3 { id = "1", firstName = "J", lastName = "R" });
        al.Add(new Employee3 { id = "2", firstName = "W", lastName = "G" });
        al.Add(new Employee3 { id = "3", firstName = "A", lastName = "H" });
        al.Add(new Employee3 { id = "4", firstName = "D", lastName = "L" });
        al.Add(new Employee3 { id = "101", firstName = "K", lastName = "F" });
        return (al);
    }
    public static Employee3[] GetEmployeesArray()
    {
        return ((Employee3[])GetEmployeesArrayList().ToArray(typeof(Employee3)));
    }
}
public class MyStringifiedNumberComparer : IEqualityComparer<string>
{
    public bool Equals(string x, string y)
    {
        return (Int32.Parse(x) == Int32.Parse(y));
    }
    public int GetHashCode(string obj)
    {
        return Int32.Parse(obj).ToString().GetHashCode();
    }
}
public class MainClass
{
    public static void Main()
    {
        Dictionary<string, string> eDictionary = Employee3.GetEmployeesArray()
        .ToDictionary(k => k.id, i => string.Format("{0} {1}", i.firstName, i.lastName), new MyStringifiedNumberComparer());
        string name = eDictionary["3"];
        Console.WriteLine("Employee whose id == \"3\" : {0}", name);
        name = eDictionary["000003"];
        Console.WriteLine("Employee whose id == \"000003\" : {0}", name);
        Console.ReadKey();
    }
}

IEquality 接口识别集合的自定义相等比较的实现。也就是说，您可以创建自己的相等定义，并指定此定义与接受IEquality Comparer接口的集合类型一起使用。在.NET Framework中，哈希表、NameValueCollection和OrderedDictionary集合类型的构造函数接受此接口。