c#之操作符

1.操作符概览

下面图中的优先级是从上往下递减，同行是从左往右递减。

操作符的本质就是函数（算法）；比如说没有操作符+，那么我们做加法的时候只能先写一个Add方法，然后调用。

操作符不能脱离与它相关联的数据类型；

比如下面的代码：

int a=1;
int b=2;
int c=a/b;

c的结果一定是整数，因为这里的除号是int类型的除号。

但是如果是下面这种，那么就是精度高的除号，也就是double的除号：

           double a = 1;
            int b = 2;
            double c = a / b;

（1）自定义一个操作符

 下面代码实现了2个人结婚，并且婚后有很多孩子。

namespace TestClass
{
    // 
    class Program
    {
        static void Main(string[] args)
        {
            Person person1 = new Person();
            Person person2 = new Person();
            person1.Name = "Deer";
            person2.Name = "Deer's wife";
            List<Person> people = Person.GetMarry(person1,person2);
            foreach(var item in people)
            {
                Console.WriteLine(item.Name);
            }
            Console.ReadKey();
        }


    } 
    class Person
    { 
        public string Name { get; set; }
        /// <summary>
        /// 结婚之后生孩子
        /// </summary>
        /// <param name="person1"></param>
        /// <param name="person2"></param>
        /// <returns></returns>
        public static List<Person> GetMarry(Person person1, Person person2)
        {
            List<Person> people = new List<Person>();
            people.Add(person1);
            people.Add(person2);
            for (int i = 0; i < 11; i++)
            {
                Person child = new Person()
                {
                    Name = person1.Name + "&" + person2.Name + "s child"
                };
                people.Add(child);
            }
            return people;
        }

    }



} 

就像之前说的，操作符的本质是算法的简记法。所以可以重写自定义的+号来表示。

namespace TestClass
{
    // 
    class Program
    {
        static void Main(string[] args)
        {
            Person person1 = new Person();
            Person person2 = new Person();
            person1.Name = "Deer";
            person2.Name = "Deer's wife";
            List<Person> people = person1 + person2;
            foreach(var item in people)
            {
                Console.WriteLine(item.Name);
            }
            Console.ReadKey();
        }


    } 
    class Person
    { 
        public string Name { get; set; }
        /// <summary>
        /// 结婚之后生孩子
        /// </summary>
        /// <param name="person1"></param>
        /// <param name="person2"></param>
        /// <returns></returns>
        public static List<Person>   operator + (Person person1, Person person2)
        {
            List<Person> people = new List<Person>();
            people.Add(person1);
            people.Add(person2);
            for (int i = 0; i < 11; i++)
            {
                Person child = new Person()
                {
                    Name = person1.Name + "&" + person2.Name + "s child"
                };
                people.Add(child);
            }
            return people;
        }

    }



} 

结果：

Deer
Deer's wife
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child
Deer&Deer's wifes child

（2）操作符的优先级

引自于：https://www.bilibili.com/video/BV13b411b7Ht?p=10