我创建的 greyhound 应用程序有问题。当我使用单选按钮选择谁在下注时(比如 Bob)并将他的赌注金额设置为 10 号狗 4，(见图 #1)当我单击“投注”时，更新“Bob 没有下任何赌注”用 description() 方法标记我得到一个错误(见图 #2)
应该发生的是它说“鲍勃没有下任何赌注”，现在应该是“鲍勃在狗 #4 上赌了 10 美元。我已经确定这是失败的，因为投注者返回 NULL，但我不知道为什么这是 Bettor 引用包含投注者姓名的 Guy 类的时候。
旁注，当比赛结束并且 Bob 获胜时，他会收到报酬，因此 PayOut() 或 Collect() 方法也不起作用。
下面是我的 3 个类和我的 Form1.cs
Greyhound.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Drawing;
using System.Windows.Forms;
namespace A_Day_at_the_Races
{
public class Greyhound
{
public int StartingPosition; //Where my PictureBox starts
public int RacetrackLength; // How long the racetrack is
public PictureBox MyPictureBox = null; //My PictureBox object
public int Location = 0; // My Location on the racetrack
public Random Randomizer; // An instance of Random
public bool Run()
{
//1. Move forward either 1,2,3 or 4 spaces at random
int moveforward = Randomizer.Next(1, 4); // declare an int called 'moveforward' will move forward 1,2,3 or 4 spaces at random
//2. Update the position of my PictureBox on the form
Point p = MyPictureBox.Location; // current location of the picture of the greyhound
p.X += moveforward;
MyPictureBox.Location = p;
//3. Return true if I won the race
if (p.X >= RacetrackLength)
return true;
else
return false;
}
public void TakeStartingPosition()
{
//Reset my location to the start line
//MyPictureBox.Location.X = StartingPosition;
StartingPosition = 0;
}
}
}
Guy.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace A_Day_at_the_Races
{
public class Guy
{
public string Name; // The guy's name
public Bet MyBet = null; // An instance of bet() that has how much he's betting
public int Cash; // How much cash he has
// these last two fields are the guy's GUI controls on the form
public RadioButton MyRadioButton; // My RadioButton
public Label MyLabel; // My Label
public void UpdateLabels()
{
//1.Set my label to my bet's description,
if (MyBet == null)
MyLabel.Text = Name + " hasnt placed any bets";
else
MyLabel.Text = MyBet.GetDescription();
//2.Set the label on my radio button to show my cash ("Joe has 43 dollars")
MyRadioButton.Text = Name + " has " + Cash + " bucks";
}
public void ClearBet()
{
//1.Reset my bet so it's zero
MyBet = null;
}
//1.Place a new bet and store it in my bet field
//2.Return true if the guy had enough money to bet
public bool PlaceBet(int Amount, int Dog)
{
this.MyBet = new Bet();
if (Cash >= Amount)
{
Cash = Cash - Amount;
MyLabel = new Label();
MyBet.Amount = Amount;
MyBet.Dog = Dog;
UpdateLabels();
return true;
}
else
{
return false;
}
}
public void Collect(int Winner)
{
if (MyBet != null)
//1.Ask my bet to pay out (hint use the bet object to do the work)
Cash += MyBet.PayOut(Winner);
}
}
}
Bet.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace A_Day_at_the_Races
{
public class Bet
{
public int Amount; // The amount of cash that was bet
public int Dog; // The number of the dog the bet is on
public Guy Bettor; // The guy who placed the bet
public string GetDescription()
{
if (Amount > 0)
return Bettor.Name + " bets " + Amount + " bucks on dog #" + Dog;
else
return Bettor.Name + " hasnt placed a bet";
}
public int PayOut(int Winner)
{
if (Winner == Dog)
return Amount;
else
return -1 * Amount;
}
}
}
Form1.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace A_Day_at_the_Races
{
public partial class Form1 : Form
{
Guy[] Bettors;
Greyhound[] Dogs;
Guy CurrentBettor;
public Form1()
{
InitializeComponent();
Random Randomizer = new Random();
//initialise all my guys and dogs
Bettors = new Guy[3];
Dogs = new Greyhound[4];
//guys
Bettors[0] = new Guy();
Bettors[0].Name = "Joe";
Bettors[0].MyRadioButton = joeRadioButton;
Bettors[0].MyLabel = joeBetLabel;
Bettors[0].Cash = 50;
Bettors[0].UpdateLabels();
Bettors[1] = new Guy();
Bettors[1].Name = "Bob";
Bettors[1].MyRadioButton = bobRadioButton;
Bettors[1].MyLabel = bobBetLabel;
Bettors[1].Cash = 75;
Bettors[1].UpdateLabels();
Bettors[2] = new Guy();
Bettors[2].Name = "Al";
Bettors[2].MyRadioButton = alRadioButton;
Bettors[2].MyLabel = alBetLabel;
Bettors[2].Cash = 45;
Bettors[2].UpdateLabels();
int StartPosition = pictureBoxDog1.Location.X;
int distance = pictureBox1.Width;
for (int i = 0; i < 4; i++)
{
Dogs[i] = new Greyhound();
Dogs[i].Randomizer = Randomizer;
Dogs[i].RacetrackLength = distance;
Dogs[i].Location = Dogs[i].StartingPosition = StartPosition;
}
Dogs[0].MyPictureBox = pictureBoxDog1;
Dogs[1].MyPictureBox = pictureBoxDog2;
Dogs[2].MyPictureBox = pictureBoxDog3;
Dogs[3].MyPictureBox = pictureBoxDog4;
CurrentBettor = Bettors[0];
}
private void RaceButton_Click(object sender, EventArgs e)
{
int winner = 0;
int num_winners = 0;
while (num_winners == 0)
{
for (int i = 0; i < Dogs.Length; i++)
{
if (Dogs[i].Run())
{
num_winners++;
winner = i + 1;
}
}
Application.DoEvents();
System.Threading.Thread.Sleep(3);
}
if (num_winners > 1)
MessageBox.Show("We have " + num_winners + " winners");
else
MessageBox.Show(" Dog #" + winner + "wins!");
for (int i = 0; i < Dogs.Length; i++)
{
Dogs[i].TakeStartingPosition();
}
for (int i = 0; i < Bettors.Length; i ++)
{
Bettors[i].Collect(winner);
Bettors[i].ClearBet();
Bettors[i].UpdateLabels();
}
numericUpDownBet.Value = numericUpDownBet.Minimum;
numericUpDownDog.Value = numericUpDownDog.Minimum;
}
private void joeRadioButton_CheckedChanged(object sender, EventArgs e)
{
SetBettor(0);
}
private void bobRadioButton_CheckedChanged_1(object sender, EventArgs e)
{
SetBettor(1);
}
private void alRadioButton_CheckedChanged_1(object sender, EventArgs e)
{
SetBettor(2);
}
private void BetsButton_Click(object sender, EventArgs e)
{
CurrentBettor.PlaceBet((int)numericUpDownBet.Value, (int)numericUpDownDog.Value);
CurrentBettor.UpdateLabels();
}
private void SetBettor(int index)
{
CurrentBettor = Bettors[index];
NameLabel.Text = CurrentBettor.Name;
if (CurrentBettor.MyBet != null)
{
numericUpDownBet.Value = CurrentBettor.MyBet.Amount;
numericUpDownDog.Value = CurrentBettor.MyBet.Dog;
}
else
{
numericUpDownBet.Value = numericUpDownBet.Minimum;
numericUpDownDog.Value = 1;
}
}
private void Form1_Load(object sender, EventArgs e)
{
minimumBetLabel.Text = "Minimum Bet $5.00";
}
private void ResetButton_Click(object sender, EventArgs e)
{
pictureBoxDog1.Location = new Point(61,32);
pictureBoxDog2.Location = new Point(61,84);
pictureBoxDog3.Location = new Point(61,131);
pictureBoxDog4.Location = new Point(61,181);
}
}
}
Form1.Designer.cs
namespace A_Day_at_the_Races
{
partial class Form1
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(Form1));
this.pictureBox1 = new System.Windows.Forms.PictureBox();
this.pictureBoxDog1 = new System.Windows.Forms.PictureBox();
this.pictureBoxDog2 = new System.Windows.Forms.PictureBox();
this.pictureBoxDog3 = new System.Windows.Forms.PictureBox();
this.pictureBoxDog4 = new System.Windows.Forms.PictureBox();
this.RaceButton = new System.Windows.Forms.Button();
this.minimumBetLabel = new System.Windows.Forms.Label();
this.joeRadioButton = new System.Windows.Forms.RadioButton();
this.bobRadioButton = new System.Windows.Forms.RadioButton();
this.alRadioButton = new System.Windows.Forms.RadioButton();
this.BetsLabel = new System.Windows.Forms.Label();
this.joeBetLabel = new System.Windows.Forms.Label();
this.bobBetLabel = new System.Windows.Forms.Label();
this.alBetLabel = new System.Windows.Forms.Label();
this.NameLabel = new System.Windows.Forms.Label();
this.BetsButton = new System.Windows.Forms.Button();
this.numericUpDownBet = new System.Windows.Forms.NumericUpDown();
this.label1 = new System.Windows.Forms.Label();
this.numericUpDownDog = new System.Windows.Forms.NumericUpDown();
this.ResetButton = new System.Windows.Forms.Button();
((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog1)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog2)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog3)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog4)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.numericUpDownBet)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.numericUpDownDog)).BeginInit();
this.SuspendLayout();
//
// pictureBox1
//
this.pictureBox1.Image = ((System.Drawing.Image)(resources.GetObject("pictureBox1.Image")));
this.pictureBox1.Location = new System.Drawing.Point(12, 12);
this.pictureBox1.Name = "pictureBox1";
this.pictureBox1.Size = new System.Drawing.Size(602, 201);
this.pictureBox1.TabIndex = 0;
this.pictureBox1.TabStop = false;
//
// pictureBoxDog1
//
this.pictureBoxDog1.Image = ((System.Drawing.Image)(resources.GetObject("pictureBoxDog1.Image")));
this.pictureBoxDog1.Location = new System.Drawing.Point(22, 21);
this.pictureBoxDog1.Name = "pictureBoxDog1";
this.pictureBoxDog1.Size = new System.Drawing.Size(75, 21);
this.pictureBoxDog1.TabIndex = 1;
this.pictureBoxDog1.TabStop = false;
//
// pictureBoxDog2
//
this.pictureBoxDog2.Image = ((System.Drawing.Image)(resources.GetObject("pictureBoxDog2.Image")));
this.pictureBoxDog2.Location = new System.Drawing.Point(22, 70);
this.pictureBoxDog2.Name = "pictureBoxDog2";
this.pictureBoxDog2.Size = new System.Drawing.Size(75, 22);
this.pictureBoxDog2.TabIndex = 2;
this.pictureBoxDog2.TabStop = false;
//
// pictureBoxDog3
//
this.pictureBoxDog3.Image = ((System.Drawing.Image)(resources.GetObject("pictureBoxDog3.Image")));
this.pictureBoxDog3.Location = new System.Drawing.Point(22, 120);
this.pictureBoxDog3.Name = "pictureBoxDog3";
this.pictureBoxDog3.Size = new System.Drawing.Size(75, 24);
this.pictureBoxDog3.TabIndex = 3;
this.pictureBoxDog3.TabStop = false;
//
// pictureBoxDog4
//
this.pictureBoxDog4.Image = ((System.Drawing.Image)(resources.GetObject("pictureBoxDog4.Image")));
this.pictureBoxDog4.Location = new System.Drawing.Point(22, 170);
this.pictureBoxDog4.Name = "pictureBoxDog4";
this.pictureBoxDog4.Size = new System.Drawing.Size(75, 24);
this.pictureBoxDog4.TabIndex = 4;
this.pictureBoxDog4.TabStop = false;
//
// RaceButton
//
this.RaceButton.Location = new System.Drawing.Point(468, 269);
this.RaceButton.Name = "RaceButton";
this.RaceButton.Size = new System.Drawing.Size(146, 73);
this.RaceButton.TabIndex = 5;
this.RaceButton.Text = "Race!";
this.RaceButton.UseVisualStyleBackColor = true;
this.RaceButton.Click += new System.EventHandler(this.RaceButton_Click);
//
// minimumBetLabel
//
this.minimumBetLabel.AutoSize = true;
this.minimumBetLabel.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.25F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.minimumBetLabel.Location = new System.Drawing.Point(9, 241);
this.minimumBetLabel.Name = "minimumBetLabel";
this.minimumBetLabel.Size = new System.Drawing.Size(0, 13);
this.minimumBetLabel.TabIndex = 6;
//
// joeRadioButton
//
this.joeRadioButton.AutoSize = true;
this.joeRadioButton.Location = new System.Drawing.Point(12, 269);
this.joeRadioButton.Name = "joeRadioButton";
this.joeRadioButton.Size = new System.Drawing.Size(85, 17);
this.joeRadioButton.TabIndex = 7;
this.joeRadioButton.TabStop = true;
this.joeRadioButton.Text = "radioButton1";
this.joeRadioButton.UseVisualStyleBackColor = true;
this.joeRadioButton.CheckedChanged += new System.EventHandler(this.joeRadioButton_CheckedChanged);
//
// bobRadioButton
//
this.bobRadioButton.AutoSize = true;
this.bobRadioButton.Location = new System.Drawing.Point(12, 293);
this.bobRadioButton.Name = "bobRadioButton";
this.bobRadioButton.Size = new System.Drawing.Size(85, 17);
this.bobRadioButton.TabIndex = 8;
this.bobRadioButton.TabStop = true;
this.bobRadioButton.Text = "radioButton1";
this.bobRadioButton.UseVisualStyleBackColor = true;
this.bobRadioButton.CheckedChanged += new System.EventHandler(this.bobRadioButton_CheckedChanged_1);
//
// alRadioButton
//
this.alRadioButton.AutoSize = true;
this.alRadioButton.Location = new System.Drawing.Point(12, 317);
this.alRadioButton.Name = "alRadioButton";
this.alRadioButton.Size = new System.Drawing.Size(85, 17);
this.alRadioButton.TabIndex = 9;
this.alRadioButton.TabStop = true;
this.alRadioButton.Text = "radioButton2";
this.alRadioButton.UseVisualStyleBackColor = true;
this.alRadioButton.CheckedChanged += new System.EventHandler(this.alRadioButton_CheckedChanged_1);
//
// BetsLabel
//
this.BetsLabel.AutoSize = true;
this.BetsLabel.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.25F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.BetsLabel.Location = new System.Drawing.Point(164, 241);
this.BetsLabel.Name = "BetsLabel";
this.BetsLabel.Size = new System.Drawing.Size(32, 13);
this.BetsLabel.TabIndex = 10;
this.BetsLabel.Text = "Bets";
//
// joeBetLabel
//
this.joeBetLabel.AutoSize = true;
this.joeBetLabel.Location = new System.Drawing.Point(164, 269);
this.joeBetLabel.Name = "joeBetLabel";
this.joeBetLabel.Size = new System.Drawing.Size(35, 13);
this.joeBetLabel.TabIndex = 11;
this.joeBetLabel.Text = "label1";
//
// bobBetLabel
//
this.bobBetLabel.AutoSize = true;
this.bobBetLabel.Location = new System.Drawing.Point(164, 293);
this.bobBetLabel.Name = "bobBetLabel";
this.bobBetLabel.Size = new System.Drawing.Size(35, 13);
this.bobBetLabel.TabIndex = 12;
this.bobBetLabel.Text = "label1";
//
// alBetLabel
//
this.alBetLabel.AutoSize = true;
this.alBetLabel.Location = new System.Drawing.Point(164, 317);
this.alBetLabel.Name = "alBetLabel";
this.alBetLabel.Size = new System.Drawing.Size(35, 13);
this.alBetLabel.TabIndex = 13;
this.alBetLabel.Text = "label1";
//
// NameLabel
//
this.NameLabel.AutoSize = true;
this.NameLabel.Location = new System.Drawing.Point(9, 359);
this.NameLabel.Name = "NameLabel";
this.NameLabel.Size = new System.Drawing.Size(0, 13);
this.NameLabel.TabIndex = 14;
//
// BetsButton
//
this.BetsButton.Location = new System.Drawing.Point(54, 354);
this.BetsButton.Name = "BetsButton";
this.BetsButton.Size = new System.Drawing.Size(75, 23);
this.BetsButton.TabIndex = 15;
this.BetsButton.Text = "Bets";
this.BetsButton.UseVisualStyleBackColor = true;
this.BetsButton.Click += new System.EventHandler(this.BetsButton_Click);
//
// numericUpDownBet
//
this.numericUpDownBet.Location = new System.Drawing.Point(135, 357);
this.numericUpDownBet.Minimum = new decimal(new int[] {
5,
0,
0,
0});
this.numericUpDownBet.Name = "numericUpDownBet";
this.numericUpDownBet.Size = new System.Drawing.Size(72, 20);
this.numericUpDownBet.TabIndex = 16;
this.numericUpDownBet.Value = new decimal(new int[] {
5,
0,
0,
0});
//
// label1
//
this.label1.AutoSize = true;
this.label1.Location = new System.Drawing.Point(214, 359);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(113, 13);
this.label1.TabIndex = 17;
this.label1.Text = "bucks on dog number ";
//
// numericUpDownDog
//
this.numericUpDownDog.Location = new System.Drawing.Point(334, 356);
this.numericUpDownDog.Maximum = new decimal(new int[] {
4,
0,
0,
0});
this.numericUpDownDog.Minimum = new decimal(new int[] {
1,
0,
0,
0});
this.numericUpDownDog.Name = "numericUpDownDog";
this.numericUpDownDog.Size = new System.Drawing.Size(79, 20);
this.numericUpDownDog.TabIndex = 18;
this.numericUpDownDog.Value = new decimal(new int[] {
1,
0,
0,
0});
//
// ResetButton
//
this.ResetButton.Location = new System.Drawing.Point(468, 349);
this.ResetButton.Name = "ResetButton";
this.ResetButton.Size = new System.Drawing.Size(146, 41);
this.ResetButton.TabIndex = 19;
this.ResetButton.Text = "Reset";
this.ResetButton.UseVisualStyleBackColor = true;
this.ResetButton.Click += new System.EventHandler(this.ResetButton_Click);
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(626, 410);
this.Controls.Add(this.ResetButton);
this.Controls.Add(this.numericUpDownDog);
this.Controls.Add(this.label1);
this.Controls.Add(this.numericUpDownBet);
this.Controls.Add(this.BetsButton);
this.Controls.Add(this.NameLabel);
this.Controls.Add(this.alBetLabel);
this.Controls.Add(this.bobBetLabel);
this.Controls.Add(this.joeBetLabel);
this.Controls.Add(this.BetsLabel);
this.Controls.Add(this.alRadioButton);
this.Controls.Add(this.bobRadioButton);
this.Controls.Add(this.joeRadioButton);
this.Controls.Add(this.minimumBetLabel);
this.Controls.Add(this.RaceButton);
this.Controls.Add(this.pictureBoxDog4);
this.Controls.Add(this.pictureBoxDog3);
this.Controls.Add(this.pictureBoxDog2);
this.Controls.Add(this.pictureBoxDog1);
this.Controls.Add(this.pictureBox1);
this.Name = "Form1";
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog1)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog2)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog3)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBoxDog4)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.numericUpDownBet)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.numericUpDownDog)).EndInit();
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
private System.Windows.Forms.PictureBox pictureBox1;
private System.Windows.Forms.PictureBox pictureBoxDog1;
private System.Windows.Forms.PictureBox pictureBoxDog2;
private System.Windows.Forms.PictureBox pictureBoxDog3;
private System.Windows.Forms.PictureBox pictureBoxDog4;
private System.Windows.Forms.Button RaceButton;
private System.Windows.Forms.Label minimumBetLabel;
private System.Windows.Forms.RadioButton joeRadioButton;
private System.Windows.Forms.RadioButton bobRadioButton;
private System.Windows.Forms.RadioButton alRadioButton;
private System.Windows.Forms.Label BetsLabel;
private System.Windows.Forms.Label joeBetLabel;
private System.Windows.Forms.Label bobBetLabel;
private System.Windows.Forms.Label alBetLabel;
private System.Windows.Forms.Label NameLabel;
private System.Windows.Forms.Button BetsButton;
private System.Windows.Forms.NumericUpDown numericUpDownBet;
private System.Windows.Forms.Label label1;
private System.Windows.Forms.NumericUpDown numericUpDownDog;
private System.Windows.Forms.Button ResetButton;
}
}
最佳答案
在 PlaceBet 方法中您忘记设置 Bettor 属性:
if (Cash >= Amount)
{
Cash = Cash - Amount;
MyLabel = new Label();
MyBet.Amount = Amount; // HERE
MyBet.Dog = Dog; // HERE
UpdateLabels();
return true;
只需在此处添加一行:
MyBet.Bettor = this;
解释/基本原理:关键是如果没有它，当“Guy”创建“Bet”时，Bet 不知道是谁创建的。在您的代码中没有任何地方设置 Bettor 字段，因此它永远没有机会设置为有意义的内容。投注将仅保留此字段中的默认 NULL 值。因为我实际上并没有阅读/跟踪所有代码，所以我认为最简单的方法是让 Bet 从一开始就知道他的主人。
关于c# - Head First C# Lab1 A Day at the Races 调用的方法未执行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12211793/