將對象設為數組返回錯誤“方法必須具有返回類型”

Question

我遵循《 Head First》一書，但無法弄清楚為什么無法聲明對象數組。 系統一直在說“方法必須具有返回類型”。 我知道我可以標記每個單個對象的不同名稱，如dog1，dog2，dog3，並使用Guy類創建對象，例如，但是我只是想知道我做錯了什么，它不能是數組dog [0]，dog [ 1]等。您能幫我嗎？

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication7
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Guy Joe = new Guy() {Money = 50}; 
        Guy Bob = new Guy() {Money = 75};
        Guy Al = new Guy() {Money = 45};


        Greyhound[] dog = new Greyhound[4];
        dog[0] = new Greyhound();
    }
    public class Guy
    {
        public int Money;

    }
    class Greyhound
    {
        public int StartingPosition;
        public int RaceTrackLengh;
        public PictureBox MyPictureBox = null;
        public Random Randomizer;
        public int Location;

        public bool Run()
        {
            Location += Randomizer.Next(5);
            MyPictureBox.Left = StartingPosition + Location;
            if (Location >= RaceTrackLengh)
            {
                TakeStartingPosition();
                return true;
            }
            else
            {
                return false;
            }

        }

        private void TakeStartingPosition()
        {
            Location = 0;
            MyPictureBox.Left = StartingPosition;
        }
    }
}

Answer 1

在構造函數中聲明它們：

public Form1()
        {
            InitializeComponent();
            Guy Joe = new Guy() {Money = 50}; 
             Guy Bob = new Guy() {Money = 75};
             Guy Al = new Guy() {Money = 45};


             Greyhound[] dog = new Greyhound[4];
             dog[0] = new Greyhound();
        }

Answer 2

問題在於，行dog[0] = new Greyhound(); 是一條語句 ，而Greyhound[] dog = new Greyhound[4]; 例如帶有初始化的字段聲明。

語句必須在方法中，但是對於您要執行的操作，還有另一種使用初始化器列表的方法：

Greyhound[] dog = new Greyhound[4]
{
    new Greyhound(),
    new Greyhound(),
    new Greyhound(),
    new Greyhound()
}

Answer 3

您不能只放這樣的代碼

Greyhound[] dog = new Greyhound[4];
dog[0] = new Greyhound();

在一個類中，它必須進入構造函數或其他方法中。

Answer 4

嘗試這個：

using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication7
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
       Guy Joe = new Guy() {Money = 50}; 
      Guy Bob = new Guy() {Money = 75};
      Guy Al = new Guy() {Money = 45};


    Greyhound[] dog = new Greyhound[4];
    dog[0] = new Greyhound();

    }
  }
public class Guy
{
    public int Money;

}
class Greyhound
{
    public int StartingPosition;
    public int RaceTrackLengh;
    public PictureBox MyPictureBox = null;
    public Random Randomizer;
    public int Location;

    public bool Run()
    {
        Location += Randomizer.Next(5);
        MyPictureBox.Left = StartingPosition + Location;
        if (Location >= RaceTrackLengh)
        {
            TakeStartingPosition();
            return true;
        }
        else
        {
            return false;
        }

    }

    private void TakeStartingPosition()
    {
        Location = 0;
        MyPictureBox.Left = StartingPosition;
    }
}
}