Program.cs

namespace WK1ConsoleApp;

class Program
{
    public static void LoopProductName(string[] productNames, string description = "Default description")
    {
        foreach (var product in productNames)
        {
            System.Console.WriteLine(product);
        }

        System.Console.WriteLine(description);
    }

    static void Main(string[] args)
    {
        string paintProductName = "Dulux";
        string description = "";

        string summary = "Summary: " + paintProductName + " and description is: " + description;

        string summaryWithIntepolation = $"Summary: {paintProductName} and description is {description}";

        System.Console.WriteLine(summary);

        System.Console.WriteLine(summaryWithIntepolation);

        int? noOfProducts = null;

        int result = noOfProducts == null ? 0 : noOfProducts.Value;

        int result2 = noOfProducts ?? 0;

        bool hasValue = noOfProducts.HasValue;

        if (hasValue)
        {
            System.Console.WriteLine(noOfProducts.Value);
        }

        int[] productPrices = { 100, 200, 300 };

        string[] productNames = { "Dulux", "Nippon", "Basic" };
        decimal productPrice = 100.05m;

        double productPriceDouble = (double)productPrice;


        int highSheenLevelPaintType = 1;
        int lowSheenLevelPaintType = 2;
        int basicSheenLevelPaintType = 3; //temp values, can not be reused!

        PaintType duluxPaintType = PaintType.HighSheenLevelPaintType;

        System.Console.WriteLine(duluxPaintType);

        System.Console.WriteLine((int)duluxPaintType);

        switch (duluxPaintType)
        {
            case PaintType.HighSheenLevelPaintType:
                description = $"Dulux is type: {PaintType.HighSheenLevelPaintType}";
                break;
            case PaintType.LowSheenLevelPaintType:
                description = $"Dulux is type: {PaintType.LowSheenLevelPaintType}";
                break;
            default:
                description = "Dulux is type: Unknown";
                break;
        }

        LoopProductName(productNames);
        PaintProduct paintProduct = new PaintProduct()
        {
            Description = "3"
        };
        // 实例化的赋值
        // 方法1： 先实例化， 再分别一行一行的赋值
        // 方法2： 通过构造函数 赋值
        // 方法3： 通过{} 赋值

        //当这个对象被创建时， 他的构造函数 会被自动调用

        // PaintProduct paintProduct2 = new PaintProduct("Dulux", 100, "Dulux Description")
        // { 
        //     Description = "3"
        // };



        //当这个对象被创建时， 他的构造函数 会被自动调用
        //paintProduct is a instance of class PaintProduct

        // paintProduct2.Description = "2";

        paintProduct.DisplayProductInfo(); //报错， 因为这些值没有值

        NipponPaint nipponPaint = new NipponPaint();
        nipponPaint.DisplayProductInfo();

    }
}

enum PaintType
{
    HighSheenLevelPaintType = 101,
    LowSheenLevelPaintType = 103,
    BasicSheenLevelPaintType = 105
} //Camel Case