Question

所以我制作了一台ATM，我要编程的第一件事就是登录界面。为了定义用户，我创建了一个User类，它由id，用户名，密码，储蓄账户和支票账户组成。在我的Windows窗体中，我创建了两个按钮，一个执行登录，另一个关闭程序。这是我的Windows窗体的代码：

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 ATM_Project
{
    public partial class Form1 : Form
    {
        List<User> users = new List<User>();
        int attempts = 3;


        public Form1()
        {
            new User() { id = 0, userName = "user1", password = "password123", savingsAcct = 2000, checkAcct = 2500 };
            new User() { id = 1, userName = "user2", password = "password234", savingsAcct = 3000, checkAcct = 4500 };
            new User() { id = 2, userName = "user3", password = "pass345", savingsAcct = 3000, checkAcct = 5000 };



            InitializeComponent();
        }

        private void exitbtn_Click(object sender, EventArgs e)
        {

            this.Close();// this button is used to close the application
        }

        private void loginbtn_Click(object sender, EventArgs e)
        {

           verification();

        }

        public void verification()
        {
            for (int i = 0; i < users.Count; i++) 
            {
                while (attempts != 0)
                {
                    if (textBox1.Text == users[i].userName && textBox2.Text == users[i].password) //checks that the username and the password match. 
                    {
                        MessageBox.Show("Your password is correct!");
                        break;

                    }
                    else
                    {
                        MessageBox.Show("Error. Your username or password are incorrect!");
                        attempts = attempts - 1;
                    }

                }
            }
        }
    }
}

我将对象放在列表中，并使用for循环遍历列表，并将第一个文本框中的用户输入与第i个位置的用户名进行比较，并将第二个文本框中用户输入的内容进行比较第i个位置的密码。如果它们匹配，它应该弹出一条消息告诉我它是正确的。如果它错了，它应该告诉我它是错的，经过三次尝试它应该停止工作。我创建了一个名为验证的公共空白，我在那里进行所有测试，我只是在登录按钮中调用它。然而它没有用。当我在文本框中键入内容并单击登录按钮时，它什么都不做。但是退出按钮确实有效。任何关于为什么会发生这种情况的见解？有什么我可以忘记的吗？

Answer 1

您似乎没有向用户列表变量添加任何内容...而不是：

public Form1()
{
    new User() { id = 0, userName = "user1", password = "password123", savingsAcct = 2000, checkAcct = 2500 };
    new User() { id = 1, userName = "user2", password = "password234", savingsAcct = 3000, checkAcct = 4500 };
    new User() { id = 2, userName = "user3", password = "pass345", savingsAcct = 3000, checkAcct = 5000 };

    InitializeComponent();
}

试

public Form1()
{
    users.Add (new User() { id = 0, userName = "user1", password = "password123", savingsAcct = 2000, checkAcct = 2500 });
    users.Add (new User() { id = 1, userName = "user2", password = "password234", savingsAcct = 3000, checkAcct = 4500 });
    users.Add (new User() { id = 2, userName = "user3", password = "pass345", savingsAcct = 3000, checkAcct = 5000 });

    InitializeComponent();
}

然后，当您遍历用户列表时，users.Count将有一个值。

Answer 2

看起来您正在定义新用户，但未将其添加到列表中。所以你循环0个用户。

您可以将Form1（）更改为

 public Form1()
        {
            users.add(new User() { id = 0, userName = "user1", password = "password123", savingsAcct = 2000, checkAcct = 2500 });
            users.add(new User() { id = 1, userName = "user2", password = "password234", savingsAcct = 3000, checkAcct = 4500 });
            users.add(new User() { id = 2, userName = "user3", password = "pass345", savingsAcct = 3000, checkAcct = 5000 });

            InitializeComponent();
        }

另请注意，this.Close（）仅关闭窗口，而不关闭应用程序。正如Winforms: Application.Exit vs Enviroment.Exit vs Form.Close

中所述

我认为此版本的验证可能更有意义：

public void verification()
{
            if (textBox1.Text == users[i].userName && textBox2.Text == users[i].password) //checks that the username and the password match. 
            {
                MessageBox.Show("Your password is correct!");
            }
            else
            {
                MessageBox.Show("Error. Your username or password are incorrect!");
                attempts -= 1;
            }

            if(attempts == 0)
            {
                Environment.Exit();
            }
}

为什么我的Windows窗体应用程序上的按钮没有工作？

2 个答案: