Calculating percentage and score in ASP.NET online examination website

Question

1.00/5 (1 vote)

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heyy i am working on online examination website i want to calculate the result percentage but its only show 0.00 nothing else

What I have tried:

protected void Page_Load(object sender, EventArgs e)
{
    SqlCommand com = new SqlCommand("Select * from [Biology]", con);
    SqlDataAdapter da = new SqlDataAdapter(com);
    DataTable dt2 = new DataTable();
    da.Fill(dt2);
    grdquestions.DataSource = dt2;
    grdquestions.DataBind();  
}
protected void examsubmit_Click(object sender, EventArgs e)
{
    int correctAnswers = 0, incorrectAnswers = 0,
    totalQuestions = grdquestions.Rows.Count;
    SqlCommand com = new SqlCommand("Select * from [Biology]", con);
    SqlDataAdapter da = new SqlDataAdapter(com);
    DataTable dt = new DataTable();
    da.Fill(dt);


   for(int i = 0; i < totalQuestions; i++)
    {
      GridViewRow row = grdquestions.Rows[i];
    string answer = dt.Rows[i]["Answer"].ToString();

  var radioButtons = new List<radiobutton>
   {
    (RadioButton)row.FindControl("Option1"),
    (RadioButton)row.FindControl("Option2"),
    (RadioButton)row.FindControl("Option3"),
    (RadioButton)row.FindControl("Option4"),
    };

foreach (var radioButton in radioButtons)
{
    if (radioButton != null)
    {
        if (radioButton.Checked)
        {
            if (radioButton.Text == answer)
                correctAnswers++;
            else
            {
                incorrectAnswers++;

                radioButton.Checked = false;
            }

        }
        else if (radioButton.Text == answer)
        {
            radioButton.Checked = true;
        }
    }
}  
} 
string correctAnswerPercentage = (correctAnswers / totalQuestions).ToString("0.00%");     
label1.text= "percentage is"+correcAnswerpercentage;
}

Posted 12-Dec-18 1:19am

AhmedHosny96

Updated 12-Dec-18 2:12am

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Comments

F-ES Sitecore 12-Dec-18 7:38am

Use the debugger to step through your code to work out what is going on. We don't have your database, your data, your inputs etc so can't run your code for you. If you are getting 0% then correctAnswers is probably 0, the debugger will confirm or deny that. If correctAnswers is 0 then step through the code and try and work out what it isn't doing that it should.

1 solution

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Richard Deeming · Answer 1 · 2018-12-12T02:12:00

Solution 1

You're using integer division, so the result will be truncated.

Change your variables to double:

C#

double correctAnswers = 0, incorrectAnswers = 0, totalQuestions = grdquestions.Rows.Count;

EDIT: You'll also need an if (!IsPostBack) { ... } test around the data-binding code in the Page_Load method. Otherwise, the user's selections will be overwritten every time, and none of the radiobuttons will be checked by the time the button click handler runs.

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        SqlCommand com = new SqlCommand("Select * from [Biology]", con);
        SqlDataAdapter da = new SqlDataAdapter(com);
        DataTable dt2 = new DataTable();
        da.Fill(dt2);
        grdquestions.DataSource = dt2;
        grdquestions.DataBind();
    }
}

Posted 12-Dec-18 2:12am

Richard Deeming

Updated 14-Dec-18 9:02am

v2

Comments

AhmedHosny96 12-Dec-18 13:53pm

after changing int to double but its not working bro ?

Richard Deeming 12-Dec-18 13:56pm

"It's not working" isn't enough information. Are you getting an error? Incorrect output? A message from the flying spaghetti monster?

Remember, we can't see your screen. All we have to go on is what you type in this little box. Help us to help you! :)

AhmedHosny96 14-Dec-18 14:38pm

i mean its still displaying 0.00% after changing to double

Richard Deeming 14-Dec-18 14:42pm

OK, that would suggest it's not counting the correct answers.

What output do you get if you use:

label1.Text= string.Format("percentage is {0} ({1}/{2})", correctAnswerPercentage, correctAnswers, totalQuestions);

AhmedHosny96 14-Dec-18 14:49pm

still its 00.0% i think its not incrementing the correct answers ?

Richard Deeming 14-Dec-18 14:55pm

Replace the line:

label1.text= "percentage is"+correcAnswerpercentage;

with:

label1.Text= string.Format("percentage is {0} ({1}/{2})", correctAnswerPercentage, correctAnswers, totalQuestions);

The output should look something like: percentage is 0.00% (0/42)

If it's not showing the numbers in brackets after the percentage, then it sounds like you need to recompile your project.

If it is showing the numbers in brackets, and the first one is 0, then you need to debug the code to see where it's going wrong. It could be that it can't find the controls; or that the text doesn't precisely match the value from the database; or that the controls aren't checked; or many other things.

If you need information on how to debug the code, Microsoft have a tutorial:
Tutorial: Learn to debug C# code using Visual Studio[^]

Richard Deeming 14-Dec-18 14:57pm

In fact, looking at your code again, it's probably that the controls aren't checked.

protected void Page_Load(object sender, EventArgs e)
{
    SqlCommand com = new SqlCommand("Select * from [Biology]", con);
    SqlDataAdapter da = new SqlDataAdapter(com);
    DataTable dt2 = new DataTable();
    da.Fill(dt2);
    grdquestions.DataSource = dt2;
    grdquestions.DataBind();  
}

You're re-binding the grid on every page load, which will overwrite any selections the user has made. You need to test the IsPostBack property first:

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        SqlCommand com = new SqlCommand("Select * from [Biology]", con);
        SqlDataAdapter da = new SqlDataAdapter(com);
        DataTable dt2 = new DataTable();
        da.Fill(dt2);
        grdquestions.DataSource = dt2;
        grdquestions.DataBind();  
    }
}

AhmedHosny96 14-Dec-18 15:12pm

its showing : percentage is 0.00% (0/42)
and i checked the IsPostBack property but nothing changed ?

Richard Deeming 14-Dec-18 15:13pm

Then you're going to need to debug your code. Set a breakpoint on the first line of the examsubmit_Click method, and step through it to see what's going wrong.

AhmedHosny96 14-Dec-18 15:38pm

bro i debugged the code starting from the exasubmit_click

the rest of the code is ok but the debugger jumped for :
if (radioButton.Checked)
{
if (radioButton.Text == answer)
{
correctAnswers++;
totalMarks += marks;
}
else
{
incorrectAnswers++;
radioButton.Checked = false;
}
}

to :

else if (radioButton.Text == answer)
{
correctAnswers++;
radioButton.Checked = true;

}
so its clear that the conditionals are not executed by the compiled ... ?

Richard Deeming 14-Dec-18 15:44pm

That just means the one you're currently looking at isn't checked. If you keep stepping through, you should get to one that is checked.

AhmedHosny96 14-Dec-18 15:51pm

sorry the problem starts from :
if (radioButton.Text == answer)
{
correctAnswers++;
totalMarks += marks;
}
else
{
incorrectAnswers++;
radioButton.Checked = false;
}

and stop until here
else if (radioButton.Text == answer)
{
correctAnswers++;
radioButton.Checked = true;

}

so what should i do .. ?

Richard Deeming 14-Dec-18 15:55pm

So the current radiobutton you're looking at isn't checked. Keep stepping through until you find one that is checked.

If none of them are checked, then there's something in your code which is overwriting the user's selection before you've read it.

AhmedHosny96 15-Dec-18 10:48am

@Richard Deeming still the issue remains unsolved what did u recommend..?

Richard Deeming 17-Dec-18 6:17am

I recommend that you debug your code. Sorry, but we can't do that for you.

AhmedHosny96 17-Dec-18 15:10pm

thank u brother for every thing i have solved the error by generating the result in different way thanks for your help again <3 big hug

Richard Deeming 17-Dec-18 15:14pm

Excellent news. Glad you got it sorted. :)

Calculating percentage and score in ASP.NET online examination website

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Solution 1

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Calculating percentage and score in ASP.NET online examination website

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