Question

我无法找到能够解答此特定情况的帖子。也许我真的很累。无论如何，我正在为WinForms进行登录验证。我有一个名为DBFunctions.cs的类，它保存数据库连接信息等。我坚持认为“C＃中的赋值的左侧必须是变量，属性或索引器”错误。请在下面找到我当前的代码。提前谢谢。

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();
    }
    }

    }
    }
    }

Answer 1

很简单，你将=（赋值运算符）与==（比较运算符）混淆。

你的意思是进入

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

（而不是= true）

但实际上，将布尔值与常量布尔值进行比较是一项冗余操作。

你应该使用：

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

Answer 2

我试图将一个对象转换为bool。我宣布bool类型的状态并返回bool所以，我需要将公共对象更改为public bool。代码如下：

<强>原始

 Initials = alphabeticallyOrderedList
    .Select((word, index) => new { Word = word, WordIndex = index })
    .GroupBy(x => x.Word[0])
    .ToDictionary(charGroup => charGroup.Key, charGroup => charGroup.First().WordIndex);

<强>校正的

{
  "id": "aabbbccdd",
  "name": "Object 1",
  "metadata": {
    "attributeA": "This is a text attribute",
    "attributeB": {
        "key1": "complex attribute",
        "key2": "complex attribute 2",
    },
    "attributeC": 1234
  }
},
{
  "id": "eeffffggghh",
  "name": "Object 2",
  "metadata": {
    "attributeA": "This is a text attribute with a different value",
    "attributeD": "Another text attribute",
    "attributeE": True
  }
}

C＃左侧的分配必须是变量，属性或索引器

2 个答案: