Question

我有第一个名为：

的班级

            Appartments[] appartments;

我想复制“Number”的值并将其粘贴到“AppartmentInfo.cs”类（我猜它们被称为参数）。

        public static void FindFloor(Appartments[] appartments, int amount,out int floorToRound,out AppartmentInfo[] AInfo)
    {
        floorToRound = 0;
        AInfo = new AppartmentInfo[Max];
        for (int i = 0; i < amount; i++)
        {
            AInfo[i].Floor1 = Convert.ToDouble(appartments[i].Number);
            Console.WriteLine(appartments[i].Number);
            if (appartments[i].Number < 27)
            {
                appartments[i].Number = 1;
            }
            else
            {

                appartments[i].Number /= 27;
            }
        }
    }

如果有需要，我可以发布整个代码。我收到错误： NullReferenceException未处理。

该行错误：

AInfo[i].Floor1 = Convert.ToDouble(appartments[i].Number);

完整代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;

namespace P3._1
 {
class Program
{
    public const int Max = 20;
    static void Main(string[] args)
    {
        int amount, AmountOfRooms, price, floor, floorToRound;
        Appartments[] appartments;
        AppartmentInfo[] AInfo;
        //AppartmentInfo AInfo = new AppartmentInfo();
        ReadData(out appartments, out amount);
        TextImput(out floor, out AmountOfRooms, out price);
        FindFloor(appartments, amount,out floorToRound,out AInfo);
        Console.ReadKey();
    }
    public static void ReadData(out Appartments[] appartments, out int amount)
    {
        amount = 0;
        appartments = new Appartments[Max];
        using (StreamReader reader = new StreamReader("C:\\Users\\Andrius\\Desktop\\Mokslams\\C#\\Pratybos\\P3\\P3.1 be konstruktoriaus\\Appartments.csv", true))
        {
            reader.ReadLine();
            string line = null;
            while (null != (line = reader.ReadLine()))
            {
                string[] values = line.Split(',');
                int number = int.Parse(values[0]);
                int area = int.Parse(values[1]);
                int rooms = int.Parse(values[2]);
                int sellingCost = int.Parse(values[3]);
                int phone = int.Parse(values[4]);

                Appartments appartmentsObj = new Appartments(number, area, rooms, sellingCost, phone);
                appartments[amount++] = appartmentsObj;
            }
        }
    }

    public static void TextImput(out int floor, out int AmountOfRooms, out int price)
    {
        AmountOfRooms = 0;
        price = 0;
        Console.WriteLine("Iveskite buto aukštą: ");
        floor = int.Parse(Console.ReadLine());
        Console.WriteLine("Iveskite kambariu skaiciu: ");
        AmountOfRooms = int.Parse(Console.ReadLine());
        Console.WriteLine("Maksimali kaina: ");
        price = int.Parse(Console.ReadLine());


    }

    public static void FindFloor(Appartments[] appartments, int amount,out int floorToRound,out AppartmentInfo[] AInfo)
    {
        floorToRound = 0;
        AInfo = new AppartmentInfo[Max];
        for (int i = 0; i < amount; i++)
        {
            AInfo[i].Floor1 = Convert.ToDouble(appartments[i].Number);
            Console.WriteLine(appartments[i].Number);
            if (appartments[i].Number < 27)
            {
                appartments[i].Number = 1;
            }
            else
            {

                appartments[i].Number /= 27;
            }
        }
    }




}

}

Answer 1

您正在尝试访问AInfo[i].Floor1属性，但如果AppartmentInfo是一个类，则AInfo数组中的每个元素都将为null。您需要先创建一个AppartmentInfo对象：

    for (int i = 0; i < amount; i++)
    {
        AInfo[i] = new AppartmentInfo
        {
            Floor1 = Convert.ToDouble(appartments[i].Number)
        };

编辑/更新：完整/可编辑程序以演示语法：

public class Program
{       
    public static void Main()
    {
        var meow = new Foo[3];

        for (int i = 0; i < 3; ++i)
        {
            meow[i] = new Foo
            {
                Bar = Convert.ToDouble("3.141"),
                Blah = "Another Test",
            };              

            if (i < 2)
            {
                meow[i].Buzz = 3;
            }
        }
    }

    class Foo
    {
        public double Bar { get; set; }
        public string Blah { get; set; }
        public int Buzz { get; set; }
    }
}

Answer 2

你的for循环从零迭代到数量 - 1然后尝试在Appartments数组中查找该索引的数组条目。

金额字段传入的值可能大于公寓数组的大小。

很难说不知道公寓阵列是什么样的，以及金额参数中的值是什么。

无法将值传递给另一个类（c＃）

2 个答案: