Program to generate Tables, trouble using Events - winforms

Question

I am doing a program in C# for kids with which kids can test their knowledge of Multiplication tables.
I cannot get the value of 'i' in the Result_Leave() function to track which value of the text box array is incorrect.
For Example:
5 X 1 = [ ] <---- an array of textboxes with name Result[i]"
the user enters the value of 5*1 in the text box and my program instantly checks if the entered value is correct or not, using the "Leave" event for the text box.
I have used an array of text boxes...
So I cannot track which Result[i] contains the incorrect value...
I have fired the function "Result_Leave" for each of the text boxes "Result[i]"
Here is the code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Tables
{
public partial class FormMain : Form
{
private System.Windows.Forms.Label[] labelNumber;
private System.Windows.Forms.Label[] labelCross;
private System.Windows.Forms.Label[] labelTableOf;
private System.Windows.Forms.Label[] labelEquals;
/*"Result" is an array of textboxes which takes the result of the multiplication from the user*/
private System.Windows.Forms.TextBox[] Result; //declaration
public FormMain()
{
InitializeComponent();
WindowState = FormWindowState.Maximized;
buttonCheckAnswers.Enabled = false;
}
private void buttonGo_Click(object sender, EventArgs e)
{
if (textBoxInput.Text == "")
{
errorProvider1.SetError(textBoxInput, "Hey! Enter a number please");
}
else
{
textBoxInput.Enabled = false;
buttonCheckAnswers.Enabled = true;
labelNumber = new System.Windows.Forms.Label[10];
labelCross = new System.Windows.Forms.Label[10];
labelTableOf = new System.Windows.Forms.Label[10];
labelEquals = new System.Windows.Forms.Label[10];
Result = new System.Windows.Forms.TextBox[10];
for (int i = 0; i < 10; i++)
{
// this snippet generates code for adding controls at runtime viz. textboxes and labels
labelNumber[i] = new Label();
this.labelNumber[i].AutoSize = true;
this.labelNumber[i].Location = new System.Drawing.Point(200, 163 + 55 * i);
this.labelNumber[i].Name = "labelNumber";
this.labelNumber[i].Size = new System.Drawing.Size(35, 13);
this.labelNumber[i].Text = (i + 1).ToString();
this.labelNumber[i].Font = new System.Drawing.Font("Comic Sans MS", 17F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.labelNumber[i].ForeColor = System.Drawing.Color.Khaki;
this.Controls.AddRange(new System.Windows.Forms.Control[] { labelNumber[i] });
labelCross[i] = new Label();
this.labelCross[i].AutoSize = true;
this.labelCross[i].Location = new System.Drawing.Point(150, 163 + 55 * i);
this.labelCross[i].Name = "labelCross";
this.labelCross[i].Size = new System.Drawing.Size(35, 13);
this.labelCross[i].Text = "X";
this.labelCross[i].Font = new System.Drawing.Font("Comic Sans MS", 17F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.labelCross[i].ForeColor = System.Drawing.Color.Khaki;
this.Controls.AddRange(new System.Windows.Forms.Control[] { labelCross[i] });
labelTableOf[i] = new Label();
this.labelTableOf[i].AutoSize = true;
this.labelTableOf[i].Location = new System.Drawing.Point(100, 163 + 55 * i);
this.labelTableOf[i].Name = "labelTableOf";
this.labelTableOf[i].Size = new System.Drawing.Size(35, 13);
this.labelTableOf[i].Text = textBoxInput.Text;
this.labelTableOf[i].Font = new System.Drawing.Font("Comic Sans MS", 17F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.labelTableOf[i].ForeColor = System.Drawing.Color.Khaki;
this.Controls.AddRange(new System.Windows.Forms.Control[] { labelTableOf[i] });
labelEquals[i] = new Label();
this.labelEquals[i].AutoSize = true;
this.labelEquals[i].Location = new System.Drawing.Point(250, 163 + 55 * i);
this.labelEquals[i].Name = "labelTableOf";
this.labelEquals[i].Size = new System.Drawing.Size(35, 13);
this.labelEquals[i].Text = "=";
this.labelEquals[i].Font = new System.Drawing.Font("Comic Sans MS", 17F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.labelEquals[i].ForeColor = System.Drawing.Color.Khaki;
this.Controls.AddRange(new System.Windows.Forms.Control[] { labelEquals[i] });
/*"Result" is an array of textboxes which takes the result of the multiplication from the user*/
Result[i] = new TextBox();
this.Result[i].BackColor = System.Drawing.Color.BlueViolet;
this.Result[i].Font = new System.Drawing.Font("Comic Sans MS", 15.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.Result[i].ForeColor = System.Drawing.SystemColors.Info;
this.Result[i].Location = new System.Drawing.Point(300, 163 + 55 * i);
this.Result[i].Name = "Result" + i;
this.Result[i].Size = new System.Drawing.Size(57, 37);
this.Result[i].TabIndex = i;
/*this is where the problem arises...*/
this.Result[i].Leave += new System.EventHandler(this.Result_Leave);// how do I send the value of 'i' to Result_Leave() function
/*Note - Result_Leave() is FIRED when the cursor moves away from the "Result" textbox*/
this.Controls.AddRange(new System.Windows.Forms.Control[] { Result[i] });
}
}
}
private void textBoxInput_TextChanged(object sender, EventArgs e)
{
errorProvider1.Clear();
}
private void radioButtonInstantChecking_CheckedChanged(object sender, EventArgs e)
{
if (radioButtonCheckAtLast.Checked == true && textBoxInput.Text!="")
{
buttonCheckAnswers.Enabled = true;
}
else buttonCheckAnswers.Enabled = false;
}
private void Result_Leave(object sender, EventArgs e)
{
/*Code for checking multiplication goes here*/
/*If multiplication result entered by the user is
*correct change the background colour of the corresponding textbox "Result[i] to GREEN else BLUE"
*as in buttonCheckAnswers_Click() function...
*/
}
private void textBoxInput_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) && e.KeyChar != '.')
{
e.Handled = true;
}
// only allow one decimal point
if (e.KeyChar == '.' && (sender as TextBox).Text.IndexOf('.') > -2)
e.Handled = true;
}
private void buttonCheckAnswers_Click(object sender, EventArgs e)
{
int score=0;
bool flag=false;
for (int i = 0; i < 10; i++)
{
if (Result[i].Text == "")
{
flag = true;
break;
}
else if ((Convert.ToInt32(Result[i].Text)) != ((Convert.ToInt32(labelNumber[i].Text) * (Convert.ToInt32(labelTableOf[i].Text)))))
{
Result[i].BackColor = System.Drawing.Color.Red;
}
else
{
Result[i].BackColor = System.Drawing.Color.Green;
score += 1;
}
}
if (score == 10)
labelComments.Text = "Well done kid! Full Marks!\nYou know your table of\n"+textBoxInput.Text+" very well"+"\nScore = "+score;
else if(flag)
labelComments.Text = "Oops! \nComplete your table kid!";
else
labelComments.Text = "Oops! \nThere are errors. \nPlease revise your tables!" + "\nYour score is : " + score;
}
}
}

Answer 1

One quick-and-dirty way to do this is to set a value in each TextBox's Tag property. In the for loop inside buttonGo_Click, you could set Result[i].Tag = i;, then in Result_Leave you could do:
int number = (int)((sender as TextBox).Tag);