分配的C#左侧必须是变量，属性或索引器 [英] C# Left-Hand Side Of An Assignment Must Be a Variable, Property or Indexer

问题描述

我真的找不到能回答这种特定情况的帖子.再加上也许我真的很累.无论如何，我正在为WinForms进行登录身份验证.我有一个名为DBFunctions.cs的类，其中包含数据库连接信息等.我在C#中遇到此分配的左侧必须是变量，属性或索引器"的错误.请在下面找到我当前的代码.预先感谢.

I couldn't really find posts that answered this specific scenario. Plus maybe I am just really tired. Anyway, I am working on a login authentication for WinForms. I have a class named DBFunctions.cs which hold database connection info etc. I am stuck with this "The left-hand side of an assignment must be a variable, property or indexer" error in C#. Please find my current code below. Thanks in advance.

namespace emsdashboard
{
public partial class Login : Form
{
public Login()
{
InitializeComponent();

}
//Contains the SQL string and other information to process
//user login.
public object VerifyUser(string userId, string password)
{
DBFunctions dbInfo = new DBFunctions();
bool status = false;
string verifyUserQry = "SELECT * FROM Employee WHERE UserName = '" + userId    + "' AND Password = '" + password + "'";
 DataTable dt = default(DataTable);
 dt = dbInfo.OpenDTConnection(verifyUserQry);
 if (dt.Rows.Count == 1)
 {
 status = true;
 }
 return status;
 }





   //When the login button is clicked. Check to see if the user
   //entered a username and/or password. Also verify the username
   //and the password are correct, else display an error message.
   private void btnLogin_Click(object sender, EventArgs e)
   {
   if(tbxUsername.Text=="" || tbxPassword.Text=="")
   {
   MessageBox.Show("Username and Password cannot be blank", "Validation Error", MessageBoxButtons.OK, MessageBoxIcon.Error);

    }
    else
    {
    if (VerifyUser(tbxUsername.Text, tbxPassword.Text) = true)
    {
    this.Hide();
    }
    }

    }
    }
    }

推荐答案

很简单，您将=(赋值运算符)与==(比较运算符)混淆了.

Nice easy one, you're confusing = (the assignment operator) with == (the comparison operator).

您将有意输入

if (VerifyUser(tbxUsername.Text, tbxPassword.Text) == true)

(而不是= true)

但是，实际上，将布尔值与恒定布尔值进行比较是多余的操作.

But really, comparing a boolean value with a constant boolean value is a redundant operation.

您应该使用:

if (VerifyUser(tbxUsername.Text, tbxPassword.Text))

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