读改善c#代码157个建议：建议10~11

目录：

• 建议10：创建对象时需要考虑是否实现比较器
• 建议11：区别对待==与Equals

一、建议10：创建对象时需要考虑是否实现比较器

比较一下基本工资：

 class Salary : IComparable
    {
        public string Name { get; set; }
        public decimal BaseSalary { get; set; }         public decimal Bonus { get; set; }
        public int CompareTo(object obj)
        {
            Salary comparer = obj as Salary;            

            if (BaseSalary > comparer.BaseSalary)
            {
                return 1;
            }
            else if (BaseSalary == comparer.BaseSalary)
            {
                return 0;
            }
            else
            {
                return -1;
            }
        }
    }

客户端调用：

 List<Salary> salaries = new List<Salary>();
            salaries.Add(new Salary() { Name = "Sun", BaseSalary = 1000 });
            salaries.Add(new Salary() { Name = "Yuan", BaseSalary = 2000 });
            salaries.Add(new Salary() { Name = "Kun", BaseSalary = 3000 });
            salaries.Add(new Salary() { Name = "Qun", BaseSalary = 3000 });
            salaries.Add(new Salary() { Name = "Sun", BaseSalary = 4000 });

            salaries.Sort();

            foreach (var s in salaries)
            {
                Console.WriteLine("【Name】：{0},【BaseSalary】：￥{1}{2}", s.Name, s.BaseSalary,System.Environment.NewLine);
            }

            Console.ReadKey();

运行：

如果不想用基本工资BaseSalary进行排序，而是以奖金Bonus进行排序，使用IComparer实现自定义比较器：

class BonusComparer : IComparer<Salary>
    {
        public int Compare(Salary x, Sarlary y)
        {           return left.Bonus.CompareTo(right.Bonus);
        }
    }

客户端提供我们上面创建的比较器：

            List<Salary> salaries = new List<Salary>();
            salaries.Add(new Salary() { Name = "Sun", BaseSalary = 1000,Bonus=4000 });
            salaries.Add(new Salary() { Name = "Yuan", BaseSalary = 2000, Bonus = 3000 });
            salaries.Add(new Salary() { Name = "Kun", BaseSalary = 3000, Bonus = 2000 });
            salaries.Add(new Salary() { Name = "Qun", BaseSalary = 3000,Bonus=4000 });
            salaries.Add(new Salary() { Name = "Dun", BaseSalary = 4000,Bonus=0 });

            salaries.Sort(new BonusComparer());

            foreach (var s in salaries)
            {
                Console.WriteLine("Name：【{0}】,BaseSalary：￥{1}，Bonus:{2}{3}", s.Name, s.BaseSalary,s.Bonus, System.Environment.NewLine);
            }

            Console.ReadKey();

输出：

二、建议11：区别对待==与Equals

两者都是指相等性，即：值相等性和引用相等性。

值类型：如果值类型相等，返回True。

引用类型：如果指向同一个引用，返回True。

很好理解，举个例子：

1、值类型：==与Equls()

            int x = 1;

            int y = 1;

            Console.WriteLine("int x=1;{0}int y=1;{0}", System.Environment.NewLine,System.Environment.NewLine);

            Console.WriteLine("x==y:{0}",x == y);

            Console.WriteLine("x.Equals(y):{0}{1}",x.Equals(y),System.Environment.NewLine);

            x = y;

            Console.WriteLine("x=y;{0}", System.Environment.NewLine);

            Console.WriteLine("x==y:{0}", x == y);

            Console.WriteLine("x.Equals(y):{0}", x.Equals(y));

            Console.ReadKey();

运行：

2、引用类型

class People
    {
        public String Name { get; set; }
    }

客户端：

            People p1 = new People() { Name = "Sun" };

            People p2 = new People() { Name = "Yuan" };

            Console.WriteLine("People p1 = new People();{0}People p2 = new People();{1}", System.Environment.NewLine, System.Environment.NewLine);

            Console.WriteLine("p1==p2:{0}", p1 == p2);

            Console.WriteLine("p1.Equals(p2):{0}{1}", p1.Equals(p2), System.Environment.NewLine);

            Console.WriteLine("------------------------------------");

            p1 = p2;

            p1.Name = "Moon";

            Console.WriteLine("p1=p2;{0}", System.Environment.NewLine);

            Console.WriteLine("p1==p2:{0}", p1 == p2);

            Console.WriteLine("p1.Equals(p2):{0}", p1.Equals(p2));

运行：

后面我们修改了p1里Name="Moon"的值，但是，p2的Name值也变成了Moon。所以，==与Equal()在比较引用类型时，引用地址一样，返回True

3、引用类型重载Equals()达到值类型比较效果

还有一点，有时我们需要我们的类型看上去和string类型类似，有值类型的感觉。所以说，我们的这个引用类型，需要重载==或者Equals()。

这里建议只重载Equals()来达到像值类型一样的比较效果。保留==，保留引用比较。例如：生活中我们认为身份证号码一样的是同一个人。

 class People
    {
        public String Name { get; set; }
        public string IDCode { get; set; }

        public override bool Equals(object obj)
        {

            People p = obj as People;

            return p.IDCode == IDCode;
        }
    }

客户端：

 People p1 = new People() { IDCode="No1" };

            People p2 = new People() { IDCode = "No1" };

            Console.WriteLine("People p1 = new People();{0}People p2 = new People();{1}", System.Environment.NewLine, System.Environment.NewLine);

            Console.WriteLine("p1.IDCode={0}", p1.IDCode);
            Console.WriteLine("p2.IDCode={0}", p2.IDCode);
            Console.WriteLine();

            Console.WriteLine("p1==p2:{0}【保留引用地址的对比】", p1 == p2);

            Console.WriteLine("p1.Equals(p2):{0}【重载比较IDCode,值类型比较效果】{1}", p1.Equals(p2), System.Environment.NewLine);

            Console.WriteLine("----------------------------------");

            p1 = p2;

            p1.IDCode = "No2";

            Console.ForegroundColor = ConsoleColor.Red;

            Console.WriteLine("p1.IDCode={0}", p1.IDCode);
            Console.WriteLine("p2.IDCode={0}", p2.IDCode);
            Console.WriteLine();

            Console.ForegroundColor = ConsoleColor.White;

            Console.WriteLine("p1=p2;{0}", System.Environment.NewLine);

            Console.WriteLine("p1==p2:{0}", p1 == p2);

            Console.WriteLine("p1.Equals(p2):{0}", p1.Equals(p2));

            Console.ReadKey();

运行：

还有，Object.ReferenceEquals方法比较实例是否相同。验证引用的相等性。