C# – Programming Skill Tester (Problem)

c++winforms

I'm working on a program that will tell what level a programmer is at beginner, intermediate, or expert based on 32 subjects from a test in Code Complete 2nd Edition. I'm using 32 check boxes and one method to tell which ones are clicked. The problem is that when I check to see if the check boxes checked property is equal to true, it gets the result before the check box actually becomes checked. Here is all of my source code (so far):

public partial class Main : Form
{
    private int baseScore = 0;

    public Main()
    {
        InitializeComponent();
    }

    private void buttonCalculateScore_Click(object sender, EventArgs e)
    {
        DetermineLevelOfProgrammer();
    }

    private void DetermineLevelOfProgrammer()
    {
        if ((baseScore >= 0) || (baseScore <= 14))
        {
            labelYourScore.Text += " " + baseScore.ToString();
            labelDescription.Text = "You are a beginning programmer, probably in your first year of computer \n"+
                                    "science in school or teaching yourself your first programming language. ";
        }

        // Do the other checks here!

    }

    // If checkbox is checked then increment base score,
    // otherwise decrement base score.
    private void checkBoxVariant_CheckedChanged(object sender, EventArgs e)
    {
        if (checkBoxVariant.Checked)
            baseScore++;
        else
            baseScore--;
    }
}

Best Solution

I'm not sure what checkBoxVariant is exacty but...

I think the problem is that checkBoxVariant is just 1 of the 32 CheckBoxes. I'm assuming you wired all 32 CheckChanged events to the checkBoxVariant_CheckedChanged method.

What it should look like is:

// If checkbox is checked then increment base score,
// otherwise decrement base score.
private void checkBoxVariant_CheckedChanged(object sender, EventArgs e)
{
   if (((CheckBox)sender).Checked)
      baseScore++;
   else
      baseScore--;
}

sender is an Object that points to the actual Object that caused the event to be raised. Since anything could raise the event, it's just an Object that must be cast to a CheckBox.

Related Solutions

C# – Programming Skill Tester (Problem) v2.0

I assume your method looks something like this:

private void clearButton_Click(object sender, EventArgs e)  
{  
    CheckBox cb = (CheckBox)sender;  
    cb.Checked = false;  
}

In this case, the "Sender" is the clear button, not a check box. Borrowing from Stormenet's answer:

private void clearButton_click(object sender, EventArgs e)  
{    
    foreach (Control c in this.Controls)   
    {  
        CheckBox cb = c as CheckBox;  
        if (cb != null)  
        {  
            cb.Checked = false;  
        }
    }
}

C# – Visual C# Programming a Login form connected to a Access Db that gives only tries to log into

There are a few helpfull answers, but I prefered to have one correct example. Your code has a few problems

It's easy to hack your database using SQL Injection
There are some issues with IDisposable, which can create memory leaks.
The code is very tight coupled to the frontend, which is almost always the case in winforms. Nevertheless I prefer to limit the calls to the UI Components.

The code I've is the following: (it has inline comments)

private int _failedLoginCounter = 0;

private void btnLogin_Click(object sender, EventArgs e)
{
    var username = txtUsername.Text;
    var password = txtPassword.Text;

    if (string.IsNullOrEmpty(username))
    {
        MessageBox.Show("Please type your Username");
        txtUsername.Focus();
        return;
    }

    if (string.IsNullOrEmpty(password))
    {
        MessageBox.Show("Please type your Password");
        txtPassword.Focus();
        return;
    }

    // Seperate the login check and make it lously coupled from the UI (= do not refer to the UI elements, instead pass the values to a method)
    CheckLogin(username, password);
}

private void CheckLogin(string username, string password)
{
    try
    {
        string constring = @"Provider=Microsoft.ACE.OLEDB.12.0; Data Source=C:\...\Auth_Credentials.accdb;";

        // You need to use a using statement since OleDbConnection implements IDisposable
        // more inf: http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbconnection(v=vs.110).aspx
        using (OleDbConnection conDataBase = new OleDbConnection(constring))
        {
            // You need to use a using statement since OleDbCommand implements IDisposable
            // more info: http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbcommand(v=vs.110).aspx
            using (OleDbCommand cmdDataBase = conDataBase.CreateCommand())
            {
                cmdDataBase.CommandText =
                    "SELECT * FROM Auth_Credentials WHERE Username=@username AND Password = @password";

                cmdDataBase.Parameters.AddRange(new OleDbParameter[]
                {
                    new OleDbParameter("@username", username),
                    new OleDbParameter("@password", password)
                });

                // Open database if not open
                if (conDataBase.State != ConnectionState.Open)
                    conDataBase.Open();

                var numberOrResults = 0;

                // You need to use a using statement since OleDbDataReader inherits DbDataReader which implements IDisposable
                // more info: http://msdn.microsoft.com/en-us/library/system.data.common.dbdatareader(v=vs.110).aspx
                using (OleDbDataReader myReader = cmdDataBase.ExecuteReader())
                {
                    while (myReader != null && myReader.Read())
                    {
                        numberOrResults++;
                    }
                }

                // If only one result was returned by the database => Succesful login
                if (numberOrResults == 1)
                {
                    MessageBox.Show("Login Successful");
                    this.Hide();
                }

                // If more than 1 result was returned by the database => Failed login
                // This is not a good idea, this situation should never occor.
                // Always make sure username + pass (or whatever you use for authentication) is unique.
                else if (numberOrResults > 1)
                {
                    MessageBox.Show("Duplicate Username or Password");
                    // increment the failed login counter
                    _failedLoginCounter++;
                }
                // No match was found in te database => Failed login
                else if (numberOrResults == 0)
                {
                    MessageBox.Show("Username or Password do not match");
                    // increment the failed login counter
                    _failedLoginCounter++;
                }
            }

        }

        // If the user has 3 failed login attempts on a row => close.
        if (_failedLoginCounter >= 3)
            this.Close();
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

For your initial question I've finished the answer of Selman22, basicly I've used a private field which keeps track of the number of failed tries. Each time the user tries to login, we check if its the 3th time. If so we close the form.

This still isn't the best approach imho, but I didnt want to change your context ;-)

I've also removed the SQL Injection possibilities by adding Parameters to the query.

To work with IDisposable implementations, you have to Dispose the object correctly. This is done in the finally block of the try/catch statement (or by a USING statement, like I did).

I hope this is helpfull, if not freel free to comment.

Best Solution

Related Solutions

C# – Programming Skill Tester (Problem) v2.0

C# – Visual C# Programming a Login form connected to a Access Db that gives only tries to log into

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