Question

此代码：

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;
using System.IO;

namespace WindowsFormsApplication2
{
public partial class Form2 : Form
{
    private void Form2_Load(object sender, EventArgs e)
    {
        pictureBox2.SizeMode = PictureBoxSizeMode.Zoom;
    }

    public Form2()
    {
        InitializeComponent();
    }
    public bool radioButtons()
    {
        if (!userRadioButton.Checked && !adminRadioButton.Checked)
        {
            MessageBox.Show("You must select an account type");
            return false;
        }
        else
        {
            return true;
        }
    }

    public void button1_Click(object sender, EventArgs e)
    {
        bool a = radioButtons();
        if (a == true)
        {
            string userName = userNameBox.Text;
            string password = passwordBox.Text;
            if (checkUsernameValid() && checkUsernameNotExist() && checkPasswordsValid() && checkPasswordsMatch())
            {
                allOK();
            }


        }   
    } 
    public void mySW()
    {
         string path = @"C:\Other\myFile.txt";
        string userName = userNameBox.Text;
        string password = passwordBox.Text;
        using (StreamWriter writer = new StreamWriter(path, true))
        {
            writer.WriteLine(userName+" "+password);
            writer.WriteLine();
            writer.Close();
            writer.Dispose();
        }
        MessageBox.Show("Thanks for registering! \n\nYou may now log in!","Registration SuccessFul");
        Application.OpenForms[0].Show();
        this.Close();
    }
    public bool checkUsernameValid()
    {
        if (userNameBox.Text == "")
        {
            MessageBox.Show("Username cannot be empty", "Invalid Username Entry");
            return false;
        }
        else
            return true;
    }
    public bool checkPasswordsMatch()
    {
        if (!passwordBox.Text.Equals(repeatPasswordBox.Text))
        {
            MessageBox.Show("Sorry, your passwords do not match, try again", "Password Error");
            passwordBox.Text = "";
            repeatPasswordBox.Text = "";
            return false;
        }
        else
            return true;
    }
    public bool checkUsernameNotExist()
    {
        var userNames = File.ReadAllLines(@"C:\Other\myFile.txt");
        if (userNames.Contains(userNameBox.Text))
        {
            MessageBox.Show(
                 "Sorry, that user name is not available, try again",
                 "Invalid Username Entry");

            userNameBox.Text = "";
            passwordBox.Text = "";
            repeatPasswordBox.Text = "";
            return false;
        }
        else
            return true;
    }
    public void allOK()
    {
        if (!userNameBox.Text.Contains("Username: " + userNameBox.Text) && passwordBox.Text == repeatPasswordBox.Text)
            {
                mySW();
            }
    }
    public bool checkPasswordsValid()
    {
        if (passwordBox.Text == "")
        {
            MessageBox.Show("Password fields cannot be empty", "Password Error");
            return false;
        }
        else
            return true;
    }

   }
}

是完整的代码，但我一直在看它。我仍然无法弄清楚为什么它让我注册相同的用户名????我不明白在调试器中它的说法是“是的，是一个匹配的字符串”，所以让我们返回true？！

注意：我已设法使用ReadAllText而不是ReadAllLines对其进行排序，但我不明白为什么行不起作用？有谁有任何想法？

PS此代码是否有更简单，更安全的方法？我想要的只是一个简单的登录屏幕lol

Answer 1

尝试从尾随和前导空格中修剪userNameBox.Text。此外，可能存在大写小写差异。

好主意可以是实际调试代码，查看列表包含的内容以及文本框中的值是什么....

Answer 2

File。readAllLines返回一个string []对象，而该对象又没有Contains方法。

我猜，使用“var”作为数据类型允许C＃VM将其强制转换为String。我建议你清楚地指定readAllLines所期望的数据类型，否则你可以通过调用readAllText替换对readAllLines的调用。

readAllText返回包含所有包含文本的单个字符串。

Answer 3

应该有！在!userNames.Contains并且更好地使用Trim（）只是因为用户可以进入空间。

if (!userNames.Contains(userNameBox.Text.Trim()))
    {                
        MessageBox.Show(
             "Sorry, that user name is not available, try again",
             "Invalid Username Entry");

        userNameBox.Text = "";
        passwordBox.Text = "";
        repeatPasswordBox.Text = "";
        return false;
    }
    else
        return true;

Answer 4

尝试现在可以使用

bool _ans;
public bool checkUsernameNotExist()
{
    string[] userNames = File.ReadAllLines(@"C:\Other\myFile.txt");
    foreach (string name in userNames)
    {
        if (name != userNameBox.Text)
        {                
            MessageBox.Show(
                 "Sorry, that user name is not available, try again",
                 "Invalid Username Entry");

            userNameBox.Text = "";
            passwordBox.Text = "";
            repeatPasswordBox.Text = "";
            _ans = false;
            return false;
        }
        else
            _ans = true;
            return true;
    }
    return _ans;
}

Answer 5

发布完整代码后，问题是清除，文件中的每一行都写为username password（不仅仅是username）。所以你的代码应该是这样的：

public bool checkUsernameNotExist()
{
    bool exist = File.ReadAllLines(@"C:\Other\myFile.txt")
                     .Any(x=>x.StartsWith(userNameBox.Text+" "));
    if (exist)
    {
        MessageBox.Show(
             "Sorry, that user name is not available, try again",
             "Invalid Username Entry");

        userNameBox.Text = "";
        passwordBox.Text = "";
        repeatPasswordBox.Text = "";
    }
    return !exist;
}

方法不会检查文件是否匹配字符串

5 个答案: