C#6 的一些新语法

people类

    public class People
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        /// <summary>
        ///C#6新语法. :8.自动实现的属性初始化器
        /// </summary>
        public DateTime BirthDay { get; set; } = DateTime.Now.AddYears(-22);

        /// <summary>
        /// C#6新语法:在属性/方法里使用Lambda表达式(Expression bodies on property-like function members)
        /// </summary>
        public string NameFormat => string.Format("姓名：{0}", "NameFormat");
        /// <summary>
        /// C#6新语法:在属性/方法里使用Lambda表达式(Expression bodies on property-like function members)
        /// </summary>
        public void Print() => WriteLine(NameFormat);
    }

1.导入静态类：

之前的写法：静态类.

            {
                Console.WriteLine("Hello!");

                Console.WriteLine($"之前的使用方式[静态类.]：{Math.Max(2, 3)}"); 
            }

C#6的写法：

            //引入命名空间
            using static System.Math;
            using static System.Console;

            WriteLine("Hello!");
            WriteLine($"现在的使用方式引入命名空间，这边直接调用：{ Max(2, 3)}");

2.字符串嵌入值

            #region 2.字符串嵌入值(String interpolation)
            {
                WriteLine($"Id：{people.Id}  姓名：{people.Name} 生日：{people.BirthDay.ToString("yyyy-MM-dd")}");
                
                WriteLine($"{(people.Age >= 25 ? "腊肉" : "鲜肉")}");

                WriteLine($"Id：{{{people.Id}}} 姓名：{{{people.Name}}}");
            }
            #endregion

3.空值运算符

            #region 3.空值运算符(Null-conditional operators) 可空判断
            {
                int? iValue = null;
                string sValue = iValue?.ToString();//string sValue = iValue.ToString();不判断会报错
                iValue = Convert.ToInt32(sValue);
                WriteLine($"iValue：{iValue}");
                string sName = "";
                WriteLine($"sName：{sName?.ToString()}");
            }
            #endregion

4.对象初始化器

            #region 4.对象初始化器(Index Initializers)
            {
                //之前通过add方法，add keyvalue进去
                {
                    IDictionary<int, string> dictOld = new Dictionary<int, string>() { };
                    dictOld.Add(1, "M");
                    dictOld.Add(2, "A");
                    dictOld.Add(3, "X");
                    foreach (var keyValue in dictOld)
                    {
                        Console.WriteLine($"key:{keyValue.Key},value:{keyValue.Value}");
                    }
                }

                {
                    IDictionary<int, string> dictOld1 = new Dictionary<int, string>()
                    {
                        { 1,"M"},{ 2,"A"},{ 3,"X"}
                    };
                }

                {
                    //通过索引的方式给字段进行初始化
                    IDictionary<int, DateTime> dictNew = new Dictionary<int, DateTime>()
                    {
                        [1] = DateTime.Now,
                        [2] = DateTime.Now.AddDays(-1),
                        [3] = DateTime.Now.AddDays(-2)
                    };
                    foreach (var keyValue in dictNew)
                    {
                        Console.WriteLine($"key:{keyValue.Key},value:{keyValue.Value}");
                    }
                }
            }
            #endregion

5.异常过滤器

            #region 5.异常过滤器(Exception filters)
            {
                int iExceptionValue = 2;
                try
                {
                    Int32.Parse("S");//Parse类型强制转换
                }
                catch (Exception e) when (iExceptionValue > 1)
                {
                    WriteLine(e.Message);
                }
            }
            #endregion

6.nameof表达式

            #region 6.nameof表达式 (nameof expressions)
            {
                /*比如我们平时喜欢写字符串的形式，如果项目越来越大，后期突然哪个不用了，
             * 使用字符串的形式维护起来就会很麻烦，用nameof就可以很好的解决，最重要的是不会影响性能！*/
                WriteLine(nameof(people));
                WriteLine(nameof(people.Name));
            }
            #endregion

7.在属性/方法里使用Lambda表达式

        /// <summary>
        /// C#6新语法:在属性/方法里使用Lambda表达式(Expression bodies on property-like function members)
        /// </summary>
        public string NameFormat => string.Format("姓名：{0}", "NameFormat");
        /// <summary>
        /// C#6新语法:在属性/方法里使用Lambda表达式(Expression bodies on property-like function members)
        /// </summary>
        public void Print() => WriteLine(NameFormat);

            #region 7.在属性/方法里使用Lambda表达式(Expression bodies on property-like function members)
            {
                people.Print();
            }
            #endregion