Program.cs

// 自动实现的属性
public class Example
{
    private string name;

    public string Name { get => name; set => name = value; }

    public string Id { get; set; }

    public int Count { get; private set; }

    public string UserId { get;}

    public Example(string userId)
    {
	this.UserId = userId;
    }
}


// 匿名类型
var user = new { name = "Gao", id = 996, height = 172.5 };	// 此时编译器会提示匿名类型， 是 new {string name, int id, double height}
Console.WriteLine(string.Format("name {0}, id {1}, height {2}", user.name, user.id, user.height));

var result = from example in examples select new { example.Name };

foreach (var item in result)
{
	Console.WriteLine(item.Name);
}

// 查询表达式
from example in examples
where example.Count > 10
orderby example.Count descending
select $"{example.Name}\t{example.Count}";

// Lambda 表达式
Func<int, int> square = x => x * x;
Console.WriteLine(square(5));

// 表达式树
Expression<Func<int>> add = () => 1 + 2;
var func = add.Compile(); // 创建一个 delegate
var answer = func(); // 调用 delegate， 得到值3
Console.WriteLine(answer);

// 扩展方法
public static class Extensions
{
    public static bool IsContainQ(this String str)
    {
        foreach (var item in str)
        {
            if (item.Equals('Q') || item.Equals('q'))
            {
                return true;
            }
        }

        return false;
    }
}

// 隐式类型本地变量
var i = “Hello CSDN！”;

// 分部方法
partial class PartialClassTest
{
    readonly string str = "Hello CSDN!";

    partial void PartialMethodTest();

    public void Display()
    {
        PartialMethodTest();
    }
}

partial class PartialClassTest
{
    partial void PartialMethodTest()
    {
        Console.WriteLine(str);
    }
}


// 对象和集合初始值设定项
public class Cat
{
    // 自动实现的属性
    public int Age { get; set; }
    public string Name { get; set; }

    public Cat()
    {
    }

    public Cat(string name)
    {
        this.Name = name;
    }
}

Cat cat = new Cat { Age = 10, Name = "Fluffy" };
Cat sameCat = new Cat("Fluffy"){ Age = 10 };

var testA = new { name = "Gao", age = 996 };

List<int> digits = new List<int> { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; 

public class MatrixTest
{
    private readonly double[,] storage = new double[3, 3];

    public double this[int row, int column]
    {
        get { return storage[row, column]; }
        set { storage[row, column] = value; }
    }
}

var identity = new MatrixTest()
{
    [0, 0] = 1.0,
    [0, 1] = 0.0,
    [0, 2] = 0.0,

    [1, 0] = 0.0,
    [1, 1] = 1.0,
    [1, 2] = 0.0,

    [2, 0] = 0.0,
    [2, 1] = 0.0,
    [2, 2] = 1.0
};