Example Application: Pledge Distribution

Description

In the .NET Framework, the spin button is represented as the up/down control. It is used to select a value in a range. This application explores its characteristics. 

Practical Learning: Creating the Application

1. Start Microsoft Visual C#
2. Create a new Windows Application named PledgeDistribution1
3. In the Solution Explorer, right-click Form1.cs and click Rename 
4. Type PledgeDistribution.cs and press Enter
5. Design the form as follows:
    

   

   Control	Text	Name	Additional Properties
   Form	Pledge Distribution		Maximize Box: False
   Label	Amount Pledged:
   TextBox	0.00	txtAmountPledged	Text Align: Right
   Label	Rotherham College:
   NumericUpDown
   Label	%
   TextBox	0.00	txtAmount1	Text Align: Right
   Label	Leicester University:
   NumericUpDown
   Label	%
   TextBox	0.00	txtAmount2	Text Align: Right
   Label	Lars Union Academy:
   NumericUpDown
   Label	%
   TextBox	0.00	txtAmount3	Text Align: Right
   Label	Message	lblMessage
   Button	Close	btnClose

6. Execute the application to test the form
7. Close the form and return to your programming environment

1. On the form, click the top numeric up-down control
2. In the Properties, click Value, type 50 and press Enter
3. In the same way, change the following properties for the controls:
    

   

   Control	Name	Additional Properties
   NumericUpDown	updAmount1	Value: 50
   NumericUpDown	updAmount2	Value: 25
   NumericUpDown	updAmount3	Value: 25

4. Double-click the top up-down control and implement its event as follows:
   

   private void updAmount1_ValueChanged(object sender, EventArgs e)
   {
       double AmountPledged = 0.00D;
       double RateAmount1, RateAmount2, RateAmount3,
              Amount1, Amount2, Amount3, Rest;
   
       // Get the current value of the amount pledged
       try
       {
           AmountPledged = double.Parse(this.txtAmountPledged.Text);
       }
       catch (FormatException)
       {
           MessageBox.Show("The amount you entered to pledge is not valid");
       }
   
       // Get the percentage that is displaying in the UpDown controls other
       // than this one
       RateAmount2 = (double)this.updAmount2.Value;
       RateAmount3 = (double)this.updAmount3.Value;
       // To make sure that the total percentage applied on all three UpDown
       // controls is = 100, get the difference left from subtracting
       // the values of the other UpDown controls from 100
       // Use that difference as the Maximum value applied on the current
       // UpDown control
       this.updAmount1.Maximum = (decimal)(100 - RateAmount2 - RateAmount3);
       // Now that we have an appropriate percentage value on the current
       // UpDown control, retrieve it
       RateAmount1 = (double)this.updAmount1.Value;
   
       // Now we can calculate the amount to apply to each institution
       Amount1 = AmountPledged * RateAmount1 / 100;
       Amount2 = AmountPledged * RateAmount2 / 100;
       Amount3 = AmountPledged * RateAmount3 / 100;
       // We need the difference, if any, left after calculating the amount 
       // pledged to each institution
       Rest = AmountPledged - Amount1 - Amount2 - Amount3;
   
       // Display the value allocated to each institution 
       this.txtAmount1.Text = Amount1.ToString("C");
       this.txtAmount2.Text = Amount2.ToString("C");
       this.txtAmount3.Text = Amount3.ToString("C");
   
       // If there is still money left, let the user know
       if (Rest > 0)
           this.lblMessage.Text = Rest.ToString("C") + " still to be used";
       else
           this.lblMessage.Text = "";
   }

5. Return to the form
6. Double-click the middle up-down control and implement its event as follows:
   

   private void updAmount2_ValueChanged(object sender, EventArgs e)
   {
       double AmountPledged = 0.00D;
       double RateAmount1, RateAmount2, RateAmount3,
              Amount1, Amount2, Amount3, Rest;
   
       try
       {
           AmountPledged = double.Parse(this.txtAmountPledged.Text);
       }
       catch (FormatException)
       {
           MessageBox.Show("The amount you entered to pledge is not valid");
       }
   
       RateAmount1 = (double)this.updAmount1.Value;
       RateAmount3 = (double)this.updAmount3.Value;
       this.updAmount2.Maximum = (decimal)(100 - RateAmount1 - RateAmount3);
       RateAmount2 = (double)this.updAmount2.Value;
   
       Amount1 = AmountPledged * RateAmount1 / 100;
       Amount2 = AmountPledged * RateAmount2 / 100;
       Amount3 = AmountPledged * RateAmount3 / 100;
       Rest = AmountPledged - Amount1 - Amount2 - Amount3;
   
       this.txtAmount1.Text = Amount1.ToString("C");
       this.txtAmount2.Text = Amount2.ToString("C");
       this.txtAmount3.Text = Amount3.ToString("C");
   
       if (Rest > 0)
           this.lblMessage.Text = Rest.ToString("C") + " still to be used";
       else
           this.lblMessage.Text = "";
   }

7. Return to the form
8. Double-click the bottom up-down control and implement its event as follows:
   

   private void updAmount3_ValueChanged(object sender, EventArgs e)
   {
               double AmountPledged = 0.00D;
               double RateAmount1, RateAmount2, RateAmount3,
                   Amount1, Amount2, Amount3,
                   Rest;
   
       try
       {
           AmountPledged = double.Parse(this.txtAmountPledged.Text);
       }
       catch (FormatException)
       {
           MessageBox.Show("The amount you entered to pledge is not valid");
       }
   
               RateAmount1 = (double)this.updAmount1.Value;
               RateAmount2 = (double)this.updAmount2.Value;
       this.updAmount3.Maximum = (decimal)(100 - RateAmount1 - RateAmount2);
               RateAmount3 = (double)this.updAmount3.Value;
   
               Amount1 = AmountPledged * RateAmount1 / 100;
               Amount2 = AmountPledged * RateAmount2 / 100;
               Amount3 = AmountPledged * RateAmount3 / 100;
               Rest = AmountPledged - Amount1 - Amount2 - Amount3;
   
       this.txtAmount1.Text = Amount1.ToString("C");
       this.txtAmount2.Text = Amount2.ToString("C");
       this.txtAmount3.Text = Amount3.ToString("C");
   
       if (Rest > 0)
          this.lblMessage.Text = Rest.ToString("C") + " still to be used";
       else
           this.lblMessage.Text = "";
   }

9. Return to the form and click (once) the Amount Pledged text box
10. In the Properties window, click the Events button
11. Double-click the Leave field to generate its event and implement it as follows:
    

    private void txtAmountPledged_Leave(object sender, EventArgs e)
    {
            // Make sure the amount pledged text box has a number
            // If it doesn't, then display the UpDown controls 
            // so the user cannot use them and cause bad events
            if( txtAmountPledged.Text == "" )
            {
                    updAmount1.Enabled = false;
                    updAmount2.Enabled = false;
                    updAmount3.Enabled = false;
            }
            else
            {
                    updAmount1.Enabled = true;
                    updAmount2.Enabled = true;
                    updAmount3.Enabled = true;
            }
    }

12. Return to the form 
13. Double-click the Close button and implement its Click event its event as follows:
    

    private void btnClose_Click(object sender, System.EventArgs e)
    {
    	Close();
    }

14. Test the application
     
    
15. Close the form and return to your programming environment