C# 7.0 新特征 Demo

using System;
using System.Collections.Generic;
using System.Text;
using static System.Console;

namespace ConsoleApp1
{
    public class CSharp7
    {
        public static int b = 0b0001;
        public static int b2 = 0b0001_00_00;
        public static long salary = 1000_000_000;
        public static decimal pi = 3.141_592_653_589m;


        private int _age;    
        public  int Age
        {
            get => _age;
            ///C#语句随意使用throw语句
            set => _age = value <= 0 || value >= 130 ? throw new ArgumentException("参数不合法") : value;
        } 

        public string Name { get; set; } = "jefft";

        /// <summary>
        /// 解构方法
        /// </summary>
        /// <param name="name"></param>
        /// <param name="age"></param>
        public void Deconstruct(out string name, out int age)
        {
            name = Name;
            age = Age;
        }

        public CSharp7()
        {

        }


        //局部函数
        public static void Outer()
        {
            WriteLine("局部方法:");
            Inner(5);
            Inner(10);
            Inner(12);

           void Inner(int len= 10)
            {             
               for(var i = 0; i< len; i++)
                {
                    Write($" {i},");
                }

                WriteLine();
            }
        }

         ~CSharp7() => Console.WriteLine("Finalized!");


        public static void Instance()
        {
            var item = new CSharp7();
            item.Age = 30;
            var (name, age) = item;
            WriteLine($"解构结果:name:{name},age: {age}");             
        }

        public static void TestNumberForamt()
        {
            WriteLine($"pi={pi}, salary={salary}, b={b}, b2={b2}");
        }

        public static void TestOutTypeVar()
        {
            WriteLine("输入一个数字:");
            var input = ReadLine();
            if (int.TryParse(input, out var result))
            {
                WriteLine("您输入的数字是：{0}", result);
            }
            else
            {
                WriteLine("无法解析输入...");
            }
        }

        public static void TestTuple()
        {
            WriteLine("Tuple::");

            ///默认
            var tuple = (12, 23);
            WriteLine($"{tuple.Item1},{tuple.Item2}");

            ///左边=>解构
            var (one, two) = (11, 22);
            WriteLine($"{one},{two}");

            ///右边
            var tuple2= (one: 1, two: 2);
            WriteLine($"{tuple2.one},{tuple2.two}");
        }
             
        public static void TestLoaclRef()
        {
            int[,] arr = { { 11, 15 }, { 22, 25 } };         

            ref var num = ref GetLocalRef(arr, c => c % 2 == 0);
            Console.WriteLine($"原数值{arr[1, 0]}");
            num = 600;
            Console.WriteLine($"新数值{arr[1, 0]}");
          
        }

        static ref int GetLocalRef(int[,] arr, Func<int, bool> func)
        {
            for (int i = 0; i < arr.GetLength(0); i++)
            {
                for (int j = 0; j < arr.GetLength(1); j++)
                {
                    if (func(arr[i, j]))
                    {
                        return ref arr[i, j];
                    }
                }
            }

            throw new InvalidOperationException("Not found");
        }


        public static void TestCaseTypeVar(object item)
        { 
            switch(item)
            {
                case int i when i< 10:
                    WriteLine($"int类型:{i},且数字小于10");
                    break;
                case int i:
                    WriteLine($"int类型:{i},且数字大于等于10");
                    break;
                case float f:
                    WriteLine($"浮点类型:{f}");
                    break;
                case string str when int.TryParse(str, out int result):
                    WriteLine($"字符串类型转为Int类型:{result}");
                    break;
                default:
                    break;
            }
        }

        public static void TestIsTypeVar(object item)
        {
            if (item is int i && i < 10)
            {
                WriteLine($"int类型:{i},且数字小于10");
            }
            else if (item is int i2)
            {
                WriteLine($"int类型:{i2},且数字大于等于10");
            }
            else if (item is float f)
            {
                WriteLine($"浮点类型:{f}");
            }
            else if (item is string str && int.TryParse(str, out int result))
            {
                WriteLine($"字符串类型转为Int类型:{result}");
            }
        }
    }
}

  static void Csharp7Test()
        {
            CSharp7.TestIsTypeVar("77");
            CSharp7.TestCaseTypeVar("88");
         
            CSharp7.TestNumberForamt();
            CSharp7.Outer();
            CSharp7.Instance();
            CSharp7.TestTuple();           
            CSharp7.TestLoaclRef();
            CSharp7.TestOutTypeVar();
            Console.ReadKey();
        }