Question

我是C＃编程的新手，我在一本教科书中看到了一个例子。

这个例子是关于抽象类的解释，但我不理解代码的一部分：

// Create an abstract class.
using System;
abstract class TwoDShape
{
    double pri_width;
    double pri_height;
    // A default constructor.
    public TwoDShape()
    {
        Width = Height = 0.0;
        name = "null";
    }
    // Parameterized constructor.
    public TwoDShape(double w, double h, string n)
    {
        Width = w;
        Height = h;
        name = n;
    }
    // Construct object with equal width and height.
    public TwoDShape(double x, string n)
    {
        Width = Height = x;
        name = n;
    }
    // Construct a copy of a TwoDShape object.
    public TwoDShape(TwoDShape ob)
    {
        Width = ob.Width;
        Height = ob.Height;
        name = ob.name;
    }
}

为什么以及何时构建对象的副本？

Answer 1

当您的类是抽象类时，您无法使用它构造对象。你需要在其他班级上做遗产。在这里你可以像这样做一个TwoDShape的矩形类herite：

    using System;

abstract class TwoDShape
{
    double pri_width;
    double pri_height;
    // A default constructor.
    public TwoDShape()
    {
        Width = Height = 0.0;
        name = "null";
    }
    // Parameterized constructor.
    public TwoDShape(double w, double h, string n)
    {
        Width = w;
        Height = h;
        name = n;
    }
    // Construct object with equal width and height.
    public TwoDShape(double x, string n)
    {
        Width = Height = x;
        name = n;
    }
    // Construct a copy of a TwoDShape object.
    public TwoDShape(TwoDShape ob)
    {
        Width = ob.Width;
        Height = ob.Height;
        name = ob.name;
    }
}
Class Rectangle:TwoDShape
{
public Rectangle(double w, double h) : base(w, h)
{
}
}

为什么以及何时构造复制对象？

1 个答案: