不确定类的内存分配 [英] not sure about memory allocation for class

问题描述

在我的2个课程中，我对FormLoad中的分配有疑问。

在下面的代码中，我对A行，B行，C行有疑问和行D

i需要你的评论。

Hellow in my 2 classes i have a doubt about the allocation in FormLoad.
In the code below ,i have doubt about Line A, Line B,Line C and line D
i need your fine comment.

	MyLine[] MyRealLine;//<---- Globalley declared 
    in FormLoad i wrote
	          MyRealLine = new MyLine[100];
              for (i = 0; i < 100; i++)
              {
                  MyRealLine[i] = new MyLine();
                  MyRealLine[i].NPOINT = new int(); //<----- Line A (is this code line neccery ? )
                  MyRealLine[i].NSIDE = new int();//<----- Line B   (is this code line neccery ? )
              }

              for (i = 0; i < 100; i++)
                  MyRealLine[i].PNT = new point[100];
              //
              for (i = 0; i < 100; i++)
                  for (j = 0; j < 100; j++)
                      MyRealLine[i].PNT[j] = new point();
              //--------------
              for (i = 0; i < 100; i++)
              MyRealLine[i].SIDE = new MySide[100];
              //
              for (i = 0; i < 100; i++)
                  for (j = 0; j < 100; j++)
                  {
                  MyRealLine[i].SIDE[j] = new MySide();
MyRealLine[i].SIDE[j].NAME=new string();//<----- Line C (if line A and B required  is required what about this string ? )
MyRealLine[i].SIDE[j].SIDESTRINGLINE=new string();//<----- Line D (if line A and line B required what about this string ?)
                  }

	
	class MyLine
    {
        private string name;
        private int npoint, nside;
        
        private MySide[] side = new MySide[100];
        private point[] pnt = new point[100];
        public MyLine() { }
        public MyLine(string Xname, int Xnpoint, int Xnside, MySide[] Xside, point[] Xpnt)
        {   
			NAME = Xname;
            NPOINT = Xnpoint;
            NSIDE = Xnside;
            //
            SIDE = Xside;
            PNT = Xpnt;
            allocate();
        }
        //---------------------------------------------------
        private void allocate()
        {
			int i;
            for (i = 0; i < 100; i++)
            {
                SIDE[i] = new MySide();
                PNT[i] = new point();
            }
        }
        //---------------------------------------------------
        public string NAME { get { return name; } set { name = value; } }
        public int NPOINT { get { return npoint; } set { npoint = value; } }
        public int NSIDE { get { return nside; } set { nside = value; } }
        //
        public MySide[] SIDE { get { return side; } set { side = value; } }
        public point[] PNT { get { return pnt; } set { pnt = value; } }
    }

    class MySide
    {
        private string name, sidestringline;
        public MySide() { }
        public MySide(string Xname, string Xsidestringline)
        {
            NAME = Xname;
            SIDESTRINGLINE = Xsidestringline;
        }
        public string NAME { get { return name; } set { name = value; } }
        public string SIDESTRINGLINE { get { return sidestringline; } set { sidestringline = value; } }
    }

推荐答案

NPOINT和NSIDE的整数分配不是必需的 - 它们是结构，所以除非你需要调用构造函数，你不需要使用 new 。



赋予NAME和SIDESTRING虽然是必要的，因为 string 是一个引用类型，它的默认值是 null - 一个空引用。因此，如果您没有指定字符串值，那么当您尝试使用它们时，如果您使用无参数构造函数，则会获得空引用异常。



但我不会不这样做，它不是很清楚。试试这个：

The allocations of integers to NPOINT and NSIDE aren't necessary - they are structs, so unless you need to call the constructor, you don't need to use new.

The assignment to NAME and SIDESTRING though are necessary, because string is a reference type, and it's default is null - an empty reference. So if you don't assign a string value then you will get null reference exceptions when you try to use them if you ever use your parameterless constructor.

But I wouldn't do it like that, it's not very clear. Try this:

MyRealLine[i].SIDE[j].NAME ="";
MyRealLine[i].SIDE[j].SIDESTRINGLINE = "";

纯粹主义者会告诉你使用它：

Purists will tell you to use this instead:

MyRealLine[i].SIDE[j].NAME = string.Empty;
MyRealLine[i].SIDE[j].SIDESTRINGLINE = string.Empty;

但是MSDN文档说它们是等价的，第一个版本更清晰！



BTW：请不要使用全部大写的属性名称：有标准它描述了名称应该是什么，属性应该以大写字母开头，其余应该是CamelCase：

But the MSDN documentation says they are equivalent, and the first version is a lot clearer!

BTW: Please don't use all upper case for property names: there are Standards which describe what names should be, and properties should start with an uppercase and the rest should be CamelCase:

public string SideStringLine { get { return _SideStringLine; } set { _SideStringLine = value; } 

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