把双打按降序排列

Question

我正在制作代表汽车零件商店的控制台应用程序，我有一个包含零件和其他耗材的目录。

当我输入“返回成本高到低”这样的命令时，如何将所有产品的成本从最高到最低，以及每个部件的名称按顺序排列？

这是相关的代码：

public class AutoPart
{
    public string Name;
    public double Cost;
}

public class Liquid : AutoPart
{
    public new string Name;
    public new double Cost;      
    public double Quarts;  
}

public class tool : AutoPart
{
    public new string Name;               
    public new double Cost;
    public double SizeInMM;
}

public class Catalogue
{
    static void Main(string[] args)
    {
        AutoPart Motorcraftoilfilter = new AutoPart();
        Motorcraftoilfilter.Name = "MotorCraft Oil Filter"; 
        Motorcraftoilfilter.Cost = 6.99;

        Liquid valvolineoil = new Liquid();
        valvolineoil.Name = "Valvoline Oil";
        valvolineoil.Cost = 8.99;
        valvolineoil.Quarts = 1;

        tool Wrench = new tool();
        Wrench.Name = "Duralast 13mm Wrench";
        Wrench.Cost = 16.99;
        Wrench.SizeInMM = 13;
    }
}

Answer 1

删除子类中不必要的字段，因为它们继承自AutoPart。

public class Liquid : AutoPart
{
    public string FluidType;  //this defines the type of fluid the product
    public double Quarts;     //this defines the quarts of the object
}

public class tool : AutoPart
{
    public double sizeinmm; //this declares the size of the tool in milimeters
}

创建一个列表以包含所有汽车零部件

List<AutoPart> AllAutoParts = new List<AutoPart>
{
    Motorcraftoilfilter,
    valvolineoil,
    Wrench,
};

然后你就可以完成这项工作

if (Console.ReadLine() == "Return Price High to low")
{
    foreach (var autopart in AllAutoParts.OrderByDescending(autopart => autopart.Cost))
        Console.WriteLine("Cost: {0}, Name: {1}", autopart.Cost, autopart.Name);
}

Answer 2

正如shingo所提到的，您可以创建基类类型列表（AutoPart）并将所有其他类型添加到其中。您只能按顺序使用基类属性，但由于它包含Cost和Name属性，因此您应该能够执行所需的操作。

然后，您可以使用OrderByDescending扩展方法（将using System.Linq添加到文件的顶部），按Cost从高到低排序：

private static void Main(string[] cmdArgs)
{
    AutoPart motorCraftOilFilter = new AutoPart();
    motorCraftOilFilter.Name = "MotorCraft Oil Filter";
    motorCraftOilFilter.Cost = 6.99;

    Liquid valvolineOil = new Liquid();
    valvolineOil.Name = "Valvoline Oil";
    valvolineOil.Cost = 8.99;
    valvolineOil.Quarts = 1;

    Tool wrench = new Tool();
    wrench.Name = "Duralast 13mm Wrench";
    wrench.Cost = 16.99;
    wrench.SizeInMM = 13;

    var catalog = new List<AutoPart>
    {
        motorCraftOilFilter,
        valvolineOil,
        wrench
    };

    // Pretent the command to order products was entered
    // You can use OrderByDescending to order the items by 
    // Cost from Highest to Lowest
    catalog = catalog.OrderByDescending(part => part.Cost).ToList();

    // Output results
    catalog.ForEach(item => Console.WriteLine(item.Name + " " + item.Cost));

    Console.Write("\nPress any key to exit...");
    Console.ReadKey();
}

---

关于设计类的方法需要注意的一点是，您不需要创建已在基类中定义的new字段。这是使用继承的原因之一是您自动继承这些字段。

此外，根据经验，您应该几乎总是使用属性而不是公共成员的字段。你可以阅读有关here的原因。

这样，您的类更简单 - 只为子类添加唯一属性：

public class AutoPart
{
    public string Name { get; set; }
    public double Cost { get; set; }
}

public class Liquid : AutoPart
{
    public double Quarts { get; set; }
}

public class Tool : AutoPart
{
    public double SizeInMM { get; set; }
}