如果用户名已经存在，它仍然会清除 [英] username still clears if it already exists

问题描述

这是我的代码，它用于登录系统，非常基本，只需将用户名和密码写入文本文件，然后在另一个表单的登录屏幕上进行比较.这是注册用户代码:

here is my code, it is for a login system, very basic, simply writes usernames and passwords to a text file, then compares them on the login screen on another form. This is the register user code:

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;
            var userNames = File.ReadAllLines(@"C:\Other\myFile.txt");
            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 and Password: {0} {1}",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()
    {
        if (userNameBox.Text.Contains("Username: " + 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;
    }

   }
}

如果我输入用户名，它会进行所有检查和注册，但是，如果用户名已经存在，它仍然允许我注册一个用户名???

If i enter a username, it does all the checks and registers BUT, it still allows me to register a username if it already exists???

推荐答案

if (userNameBox.Text.Contains("Username: " + userNameBox.Text))

我对这条线感到困惑.(这一行给出任何时间相同的结果，如 True )

I am confused this line . ( this line give any time same result like True )

但我给你一个想法

.将注册的值存储在数据库中，然后用户第二次给出相同的用户名，然后使用 sql 查询检查用户名是否已存在.

. Store registered values in a DataBase , Then second time the user give same user name , Then check the username already exist by using sql query .

查看此之前的讨论:检查用户名是否已存在于数据库中

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