passing button as a parameter in C#

Question

I'm new to C# and I want to practise my skills on using parameters however I ran into a little trouble. I am designing a system where the system should view each question from the database whenever the student clicks on the 'view' button.

OBJECTIVE:

what I want to achieve is that when the user clicks on the button which is labelled 'next'. The system should 'view; the next question onto the datagrid. I thought maybe I should make a query which says something like "select question from ... where questionID = btnView. And maybe have a function where whenever the user clicks on the button it passes 1,2,3...10 as questionID (as there are 10 questions)

this is my C# Code:

try
{
string mydbConnection = "datasource=localhost;port=3306;Initial Catalog=project;username=***;password=***;";
MySqlConnection connDB = new MySqlConnection(mydbConnection);
MySqlCommand cmdDataBase = new MySqlCommand("SELECT questions.question, questions.answer FROM questions WHERE questionID ='" + questionID +  "' ;",connDB);
connDB.Open();
MySqlDataAdapter sda = new MySqlDataAdapter();
sda.SelectCommand = cmdDataBase;
DataTable dbdataset = new DataTable();
sda.Fill(dbdataset);
BindingSource bSource1 = new BindingSource();
sda.Update(dbdataset);
bSource1.DataSource = dbdataset;
dataGridView1.DataSource = bSource1;
sda.Update(dbdataset);
this.dataGridView1.Columns[3].Visible = false;
this.dataGridView1.Columns[0].Visible = false;
connDB.Close();
}

and this is my button function to get each 'questionID'

private void button1_Click(object sender, EventArgs e)
{
   for (int i = 1; i >= 10; i++)
  {
    int questionID = i;
  }
  viewQuestion(questionID);
}

questionID does not exist in the current context.

NOTE:

The stuff on the datagrid WORKS I just want it to view each question when the user clicks on the button.

EDIT:

  int questionID =  0;
  for (int i = 1; i >= 10; i++)
  {
    int questionID = i;
  }
  viewQuestion(questionID);

causes:

A local or parameter named 'questionID' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter

For more information about accessibility of variables you should read Variable and Method Scope in Microsoft .NET — Mong Zhu
– Mong Zhu, Commented Mar 1, 2017 at 7:28

sujith karivelil · Accepted Answer · 2017-03-01 07:29:26Z

3

when the user clicks on the button which is labelled 'next'. The system should 'view'.

So there is no need for a loop in a single click, You have to make the questionID as a global variable in the same class, and increment the value of questionID in each click. which means you can do something like this:

int questionID = 0;   // Global variable
private void button1_Click(object sender, EventArgs e)
{
   if(questionID <=10)
   {
      viewQuestion(questionID);
      questionID++;
   }
   else
   {
      // Display message that question over
   }
}

edited Mar 1, 2017 at 7:29

answered Mar 1, 2017 at 7:26

sujith karivelil

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3 Comments

mrogal.ski Over a year ago

I would suggest not global but make it a member field.

sujith karivelil Over a year ago

@m.rogalski, of course it would be a field declared under the scope of the class.

mrogal.ski Over a year ago

But saying global means it wont be a member field but ( unique for each instance ) but one unified for all modules in that application scope.

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