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CS7ex Menus and Methods - Programming Example |
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CS7ex Menus and Methods - Programming Example |
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CS7ex is an example that is demonstrated in the structured class after the lecture on Menus, Dialog Boxes, and Methods. The source code listed below is then reviewed in detail. Students should referred to this code when completing their CS7 assignment. Students are NOT required to create and submit this project, but students may download and expand the self-extracting CS7ex archive into their own workspace if they like.
CS7ex Sample Form:
Source Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
//CS7ex by Your Name - CIS162AD
/*
This project is a re-write of CS5ex using Menus, Dialog Boxes,
and Methods. Methods are used to calculate extended price, sales tax,
total due, and average sales.
*/
namespace CS7ex
{
public partial class CS7exForm : Form
{
public CS7exForm()
{
InitializeComponent();
}
//Declare class-level variables and constants
//Class variables are initialized to zero when declared
int cintOrderCount;
decimal cdecGrandTotal;
const decimal cdecTAX_RATE = 0.08M;
const decimal cdecDISCOUNT_RATE = .98M; //98% of the price is a 2% discount
const decimal cdecGROUND_SHIPPING_RATE = 5.00M;
const decimal cdecTHREE_DAY_SHIPPING_RATE = 7.00M;
const decimal cdecNEXT_DAY_SHIPPING_RATE = 10.00M;
private void btnCalculate_Click(object sender, EventArgs e)
{
// declare method variables
int intQuantity;
decimal decPrice;
decimal decExtendedPrice;
decimal decSalesTax;
decimal decShipping;
decimal decTotalDue;
decimal decAverageOrder;
//Input:
//Use nested try-catch blocks to get the input values
try
{
//Use a try-catch block to catch non-numeric values
intQuantity = int.Parse(txtQuantity.Text);
decPrice = decimal.Parse (txtPrice.Text);
//Process:
//We now have a numeric quantity and price.
//Check if values are within the range
if (intQuantity >= 1 && intQuantity <= 50)
if (decPrice >= 5.00M && decPrice <= 15.00M)
{
//Values are valid
//Perform calculations using Methods
//Local values are sent to the methods through the arguments
//Local variables are assigned the values returned by each method
decExtendedPrice = calcExtendedPrice(intQuantity, decPrice);
decSalesTax = calcSalesTax(decExtendedPrice);
decShipping = setShipping( );
//The 4th argument is a call-by-reference, so the value is
//"returned" through the argument. See comments in method.
calcTotalDue(decExtendedPrice, decSalesTax, decShipping, out decTotalDue);
//Accumulate summary totals
cdecGrandTotal += decTotalDue;
cintOrderCount += 1;
decAverageOrder = calcAverage( );
//Output:
//We now have all of the values to display
lblExtendedPrice.Text = decExtendedPrice.ToString("C"); //Currency
lblSalesTax.Text = decSalesTax.ToString("C");
lblShipping.Text = decShipping.ToString("C");
lblTotalDue.Text = decTotalDue.ToString("C");
lblGrandTotal.Text = cdecGrandTotal.ToString("C");
lblNumberOfOrders.Text = cintOrderCount.ToString("N0"); //N and a Zero
lblAverageOrder.Text = decAverageOrder.ToString("C");
txtQuantity.Focus( ); //get ready for next input
}
else
{
//Handle invalid price
MessageBox.Show("Price must be between $5.00 and $15.00. ",
"Data Entry Error", MessageBoxButtons.OK,
MessageBoxIcon.Exclamation);
txtPrice.SelectAll( );
txtPrice.Focus( );
}//endif
else
{
//Handle invalid quantity
MessageBox.Show("Quantity must be between 1 and 50. ",
"Data Entry Error", MessageBoxButtons.OK,
MessageBoxIcon.Exclamation);
txtQuantity.SelectAll( );
txtQuantity.Focus( );
}//endif
}
//Handle exceptions for quantity and price
catch (FormatException err)
{
MessageBox.Show("Quantity or Price not numeric. Enter again. "
+ err.Message, "Data Entry Error", MessageBoxButtons.OK,
MessageBoxIcon.Exclamation);
txtQuantity.SelectAll( );
txtQuantity.Focus( );
}
//Handle any other exceptions.
catch(Exception err)
{
MessageBox.Show("Unexpected Error: " + err.Message);
}
}//end of btnCalculate
private void btnClearForm_Click(object sender, EventArgs e)
{
//Use Clear or null string "" for TextBoxes, but
//only use null string "" for Labels
txtQuantity.Clear(); //Clear
txtPrice.Clear();
lblExtendedPrice.Text = ""; //null string
lblSalesTax.Text = "";
lblShipping.Text = "";
lblTotalDue.Text = "";
lblGrandTotal.Text = "";
lblNumberOfOrders.Text = "";
lblAverageOrder.Text = "";
radGround.Checked = true;
chkSalesTax.Checked = false;
cdecGrandTotal = 0; //Reset Accumulators
cintOrderCount = 0;
txtQuantity.Focus();
}//end of btnClearForm
private void btnExit_Click(object sender, EventArgs e)
{
this.Close();
}//end of btnExit
//calculation methods
private decimal calcExtendedPrice(int intQuantity, decimal decPrice)
{
//Variables listed as arguments are declared as local variables
//Declare additional local variables in the body if needed
//Discount Rate is a class (global) variable, so it is not an argument
//
//Instead of having multiple return statements, the result of the
//if statement is stored and then returned at the end of the method
decimal decExtendedPrice;
if (intQuantity > 25)
decExtendedPrice = intQuantity * (decPrice * cdecDISCOUNT_RATE);
else
decExtendedPrice = intQuantity * decPrice;
return decExtendedPrice;
}
private decimal calcSalesTax(decimal decExtendedPrice)
{
//Tax Rate is a class (global) variable, so it is not an argument
//When the intermediate result is not needed,
// the calculation may be placed in the return statement
if (chkSalesTax.Checked == true)
return (decExtendedPrice * cdecTAX_RATE);
else
return 0M; //return a zero
}
private decimal setShipping( )
{
//return the shipping rate
if (radNextDay.Checked == true)
return (cdecNEXT_DAY_SHIPPING_RATE);
else if (radThreeDay.Checked == true)
return (cdecTHREE_DAY_SHIPPING_RATE);
else
return (cdecGROUND_SHIPPING_RATE);
}
private void calcTotalDue(decimal decExtendedPrice, decimal decSalesTax,
decimal decShipping, out decimal decTotalDue)
{
//void means that a value will not be returned through the return statement.
//Call-by-reference arguments can be ref or out.
//ref means that the variable will be initialized before the call.
//out means that the variable may not have been initialized, and
// that the current method will be assigning a value to the variable.
// out prevents the compiler from generating an error.
decTotalDue = decExtendedPrice + decSalesTax + decShipping;
return;
}
private decimal calcAverage( )
{
//Grand total and count are class variables so they are not passed as arguments.
return (cdecGrandTotal / cintOrderCount);
}
//Menu options
//Implement Calculate Menu option by calling existing button method
private void mnuEditCalculate_Click(object sender, EventArgs e)
{
btnCalculate_Click(sender, e);
}
//Implement Clear Form Menu option by calling existing button method
private void mnuEditClearForm_Click(object sender, EventArgs e)
{
btnClearForm_Click(sender, e);
}
private void mnuExit_Click(object sender, EventArgs e)
{
this.Close();
}
private void mnuEditFont_Click(object sender, EventArgs e)
{
//fontDialog1 object is created using the FontDialog
//control on the form, otherwise need to create here:
// FontDialog fontDialog1 = new FontDialog();
//Use the current settings as the default in the dialog box
fontDialog1.Font = lblGrandTotal.Font;
//Display dialog box so user can pick a font
//Apply the font chosen to the Totals section if not Canceled
if (fontDialog1.ShowDialog() != DialogResult.Cancel)
{
lblGrandTotal.Font = fontDialog1.Font;
lblNumberOfOrders.Font = fontDialog1.Font;
lblAverageOrder.Font = fontDialog1.Font;
}
}
private void mnuEditColor_Click(object sender, EventArgs e)
{
//colorDialog1 object is created using the ColorDialog
//control on the form, otherwise need to create here:
// ColorDialog colorDialog1 = new ColorDialog();
//Use the current settings as the default in the dialog box
colorDialog1.Color = lblGrandTotal.ForeColor;
//Display dialog box so user can pick a color
//Apply the color chosen to the Totals section if not Canceled
if (colorDialog1.ShowDialog() != DialogResult.Cancel)
{
lblGrandTotal.ForeColor = colorDialog1.Color;
lblNumberOfOrders.ForeColor = colorDialog1.Color;
lblAverageOrder.ForeColor = colorDialog1.Color;
}
//Note on FontDialog and Color:
//A color selector may be added to the FontDialog if the only
//only color options desired are the 16 basic colors. Before showing
//the FontDialog box in the mnuEditFont method above, activate
//the color option:
// fontDialog1.ShowColor = true;
//and set the Color to the currently selected fore color:
// fontDialog1.Color = lblGrandTotal.ForeColor;
//After the user selects the a color, apply the color:
// lblGrandTotal.ForeColor = fontDialog1.Color;
//
//However, ColorDialog must be used for custom colors.
//AutoFullOpen is set to true by default, which is the
//property that allows custom colors to be defined.
}
//Context Menu options attached to form
private void contextMnuFont_Click(object sender, EventArgs e)
{
mnuEditFont_Click(sender, e);
}
private void contextMnuColor_Click(object sender, EventArgs e)
{
mnuEditColor_Click(sender, e);
}
}//end of class
}//end of namespace