What does the following code do, assuming that dblValue1 and dblValue2 are both declared as doubles?



 try

 {

 dblValue1 = Double.Parse( txtInput1.Text );

 dblValue2 = Double.Parse( txtInput2.Text );



 txtOutput.Text = Convert.ToString( dblValue1 * dblValue2 );

 }



 catch ( FormatException formatExceptionParameter )

 {

 MessageBox.Show(

 "Please enter decimal values.",

 "Invalid Number Format",

 MessageBoxButtons.OK, MessageBoxIcon.Error );

 }

This code multiplies two doubles if both inputs in txtInput1 and txtInput2 can be converted to type double (that is, they are decimal or integer values). Otherwise it displays an error message dialog that informs the user to enter decimal values in the TextBoxes. The complete code reads:




 // Multiplier.cs





 using System;


 using System.Drawing;


 using System.Collections;


 using System.ComponentModel; 


 using System.Windows.Forms;


 using System.Data;





 namespace Multiplier


 {


 /// 


 /// Summary description for FrmMultiplier.


 /// 



 public class FrmMultiplier : System.Windows.Forms.Form


 {


 // Label and TextBox for first value


 private System.Windows.Forms.Label lblValue1;


 private System.Windows.Forms.TextBox txtInput1;





 // Label and TextBox for second value


 private System.Windows.Forms.Label lblValue2;


 private System.Windows.Forms.TextBox txtInput2;





 // Label and TextBox for output


 private System.Windows.Forms.Label lblProduct;


 private System.Windows.Forms.TextBox txtOutput;





 // Button to perform multiplication


 private System.Windows.Forms.Button btnMultiply;





 /// 


 /// Required designer variable.


 /// 



 private System.ComponentModel.Container components = null;





 public FrmMultiplier()


 {


 //


 // Required for Windows Form Designer support


 //


 InitializeComponent();





 //


 // TODO: Add any constructor code after InitializeComponent


 // call


 //


 }





 /// 


 /// Clean up any resources being used.


 /// 



 protected override void Dispose( bool disposing )


 {


 if( disposing )


 {


 if (components != null)


 {


 components.Dispose();


 }


 }


 base.Dispose( disposing );


 }





 // Windows Form Designer generated code





 /// 


 /// The main entry point for the application.


 /// 



 [STAThread]


 static void Main()


 {


 Application.Run( new FrmMultiplier() );


 }





 // handles btnMultiply's Click event


 private void btnMultiply_Click(


 object sender, System.EventArgs e )


 {


 double dblValue1;


 double dblValue2;





try


{


dblValue1 = Double.Parse( txtInput1.Text );


dblValue2 = Double.Parse( txtInput2.Text );


txtOutput.Text =


Convert.ToString( dblValue1 * dblValue2 );


}


catch ( FormatException formatExceptionParameter )


{


MessageBox.Show(


"Please enter decimal values.",


"Invalid Number Format",


MessageBoxButtons.OK, MessageBoxIcon.Error );


}





 } // end method btnMultiply_Click





 } // end class FrmMultiply


 }