Icomparable和Icomparable的区别

IComparable<T>
定义由“值类型或类实现”的通用的比较方法，以为排序实例创建类型特定的比较方法。
成员： CompareTo 比较当前对象和同一类型的另一对象。

IComparer<T>
定义类型为比较两个对象而实现的方法。
成员： Compare 比较两个对象并返回一个值，指示一个对象是小于、等于还是大于另一个对象。

从表面看IComparable<T>是排序时使用 IComparer<T>只是比较

对于这两个接口可能对于初学者来说易混淆。

下面通过示例来来看下IComparable<T>和ICompare<T>的区别（示例中使用IComparable和ICompare接口）

对于IComparable接口，它一般是和类绑定在一起的。往往它的实现就存在于将实进行比较的类中，并实现的函数是CompareTo();

而对于ICompare来说，则不同于上一个接口，它往往独立于要比较的类,在些类中实现的函数是Compare(),并且它的实现也常常用CompareTo()来帮助实现。

下面来看看一个实例：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Collections;

namespace Test
{
    public class Man:IComparable 
    {
        public Man()
        {
            sex="unknow";
            year=0;
        }
        public Man(string sex,int year)
        {
            this.sex=sex;
            this.year=year;
        }
        public int CompareTo(object obj)
        {
            Man other=obj as Man;
            int result=this.sex.CompareTo(other.sex);
            if (result == 0)
            {
                result = this.year.CompareTo(other.year);
                return result;
            }
            return result;
        }
        public string sex;
        public int year;
    }
    public class ManComparer : IComparer
    {
        public enum ManComparerType
        {
            sex, year
        }
        private ManComparerType type;
        public ManComparer(ManComparerType type)
        {
            this.type = type;
        }
        public int Compare(object a, object b)
        {
            Man x = a as Man;
            Man y = b as Man;
            switch (type)
            {
                case ManComparerType.sex:
                    return x.sex.CompareTo(y.sex);
                case ManComparerType.year:
                    return x.year.CompareTo(y.year);
                default:
                    throw new ArgumentException("the wrong type:");
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Man[] men ={
                          new Man("mail",4),
                          new Man("mail",5),
                          new Man("femail",67),
                          new Man("femail",45),
                          new Man("mail",58)
                 
                      };
            foreach (Man p in men)
            {
                Console.WriteLine("he is a " + p.sex + " and is " + p.year);
            }
            Console.WriteLine("\n__________first______________\n");
            Array.Sort(men, new ManComparer(ManComparer.ManComparerType.sex));
            foreach (Man p in men)
            {
                Console.WriteLine("he is a " + p.sex + " and is " + p.year);
            }
            Console.WriteLine("\n__________second_____________\n");
            Stopwatch sw = new Stopwatch();
            sw.Start();
            Array.Sort(men);
            sw.Stop();
            Console.WriteLine("it takes {0}",sw.Elapsed.ToString());
            foreach (Man p in men)
            {
                Console.WriteLine("he is a " + p.sex + " and is " + p.year);
            }

        }
    }
}

此实例用两个接口对同一个数组进行比较排序。从实现上看可以很清晰地看出它们之间的细微差别。