Creating an event driven computer program using C# Level 2 Notes for City & Guilds 7540 Unit 008 Written for Microsoft Visual C# 2005 Express

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1 Creating an event driven computer program using C# Level 2 Notes for City & Guilds 7540 Unit 008 Written for Microsoft Visual C# 2005 Express Version 1

2 Tench Computing Ltd Pines Glendale Road Burgess Hill West Sussex RH15 0EJ Web address: address: About the author: Jackie Tench MSc, ACIB, Cert Ed Jackie started her working career in branch banking with the Midland Bank (now HSBC) and was transferred to their Computing Department after achieving 100% in their ability test for programmers. She then worked for more than a decade in this department and was one of the first women to achieve a junior management grade at the age of 21. She attended a significant number of IBM programming training courses during her time there. Jackie was the first woman to pass the ACIB (Associate Chartered Institute of Bankers) examinations in the Midland Bank (HSBC) and the youngest person at 21 years of age. Jackie then left to raise a family but still found time to teach part-time at a college in Sheffield and to obtain a MSc in Computing and a Cert Ed in teaching. When her children were old enough Jackie returned to work full-time and was a Senior Lecturer in Software Engineering and Computer Studies at a college in Brighton for nearly 10 years teaching all levels up to and including HND. Therefore, Jackie has considerable business knowledge and qualifications plus wide experience in practical computing and training covering areas such as structured design, analysis, coding, testing and implementing software applications plus training students to fulfil an important role in the computer industry. Jackie has worked as a consultant for several blue chip companies and examination boards using her software engineering and educational training skills and is now one of the foremost experts in computing with an extensive knowledge of programming languages and applications. Copyright 1999 Tench Computing Ltd Microsoft, Windows, Windows NT or other Microsoft products referenced herein are either the trademarks or registered trademarks of the Microsoft Corporation. Other trademarks for products referenced herein are also acknowledged. All rights are reserved and no part of this training manual may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the purchase of a licence. This training manual is sold subject to licence and on condition that it shall not, by way of trade or otherwise, be lent, re-sold, hired out or otherwise circulated without the prior consent of Tench Computing Ltd in any form of binding or cover other than that in which it is issued and without a similar condition being imposed on the subsequent purchaser. Any program listings within this training manual may be entered, stored and executed in a computer but they may not be reproduced for publication. Version 1

3 Contents Page C# development environment... 1 Toolbars Standard toolbar... 3 Toolbox... 5 Components of a program Event functions... 9 Solution Explorer... 9 Form Design Window Code Window Properties Window Chapter 2 Objectives Demo program Create a new project Rename and save the form file Solution Explorer window Change the property of the form Properties Change the Name property of the form Change the size of the form Save the files Add the Exit button to the frmdemo form Toolbox window Place the Exit button on the form Change the Name property of the Exit button Change the property of the Exit button Change the location of the Exit button Change the Font properties of the Exit button Add the other buttons to the frmdemo form Change the Name properties Change the properties Resize the buttons Change the Font properties Add a Box to the frmdemo form Change the properties of the Box Attach code to the objects Attach code to the Exit button Code for the btnexit_click() event function Execute the Demo program Attach code to the Display button Attach code to the Clear button Execute the Demo program Executable file (Demo.EXE) Build a form from a table Questions Tench Computing Ltd Version L2 1

4 Chapter 3 Objectives CHOICE program Enter the code of the CHOICE program Execute the CHOICE program Enter more code Execute the CHOICE program How the CHOICE program works Comment CheckedChanged() event function Scroll bar Scroll program Create the form Code of the Scroll program Execute the Scroll program Minimum and Maximum properties of the scroll bar Value property of the scroll bar Keyboard focus Attach more code to the Scroll program Scroll bar properties Minimum and Maximum properties SmallChange and LargeChange properties Name conventions for controls Questions Chapter 4 Objectives Variables Arithmetic operators MULTIPLY program Arithmetic operator precedence Relational operators Decision statements if else construct switch statement Loops while loop do while loop for loop ADD program Execute the ADD program How the ADD program works TIMER program Execute the TIMER program How the TIMER program works Modify the TIMER program Execute the TIMER program Questions Tench Computing Ltd Version L2 1

5 Chapter 5 Objectives GroupBox control Enter the code of the GROUP program Debugging Compiler Executable file (EXE) Syntax errors Reserved words Logical errors Run-time errors Breakpoint and watches Check the value of a variable Add Watch Refresh() method Idle time GroupBox control Select multiple objects Lasso objects Print a code listing Print a form Question Chapter 6 Objectives Menus MENU program Create the menu Enter the code of the MENU program Add a separator bar to a menu Check marks Make a menu item invisible Questions Chapter 7 Objectives MessageBox class Show() method MESSAGE program Enter the code AcceptButon property CancelButton property Object Browser Questions Chapter 8 Objectives PictureBox control Stand-alone application Different types of picture files Bitmap files Icon files Move controls Tench Computing Ltd Version L2 1

6 PICTURE program Code the PICTURE program MOVEPIC program Code the MOVEPIC program Help facilities Questions Chapter 9 Objectives COUNT program Modify the COUNT program TabIndex property TabStop property Cursor property ComboBox control Colour constants COMBO program ListBox control Questions Chapter 10 Objectives Logical operators AND OR LOGICAL program Testing Purpose of testing Test data Evidence of compliance LOGICAL program test data Single dimension array Declare an array Access array elements Initialise an array using a loop Access and output values from an array try catch finally Questions Chapter 11 Objectives PasswordChar property QUOTE program String formats Console.WriteLine() method Locate the EXE file Questions Chapter 12 Objectives FontDialog control ShowDialog() method ColorDialog control ShowDialog() method Tench Computing Ltd Version L2 1

7 FullOpen property Font and Colour program File handling OpenFileDialog control ShowDialog() method FileName property Filter property FilterIndex property ShowReadOnly property DefaultExt property SaveFileDialog control OverwritePrompt property CheckFileExists property RichBox control SelectionAlignment property SelectionFont property SelectionColor property WordWrap property Dock property Locked property Sequential file LoadFile() method SaveFile() method EDITOR program DateTimePicker control Format property CustomFormat property Anchor property DATE program ToolStrip control TOOLSTRIP program Questions Sample assignment Sample assignment Sample questions Appendix A C# Programming Reference Guide Appendix B Tench Computing Ltd Version L2 1

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9 Objectives Chapter 11 Use the PasswordChar property Use the Console.WriteLine() method Locate the EXE file PasswordChar property The PasswordChar property of a text box is used to specify which character is to be displayed when a password is entered. The character is displayed in the text box so that when the password is entered it is not visible on the screen. Instead for every character entered by the user the password character is displayed. QUOTE program The Quote program is to provide a quote on the screen. Before the quote can be completed the user has to enter a password. Create a new project, save the project as QUOTE and the form as FormQUOTE.cs. Build the form from the following table. Object Property Setting Form Name frmquote Quote program Size 496,304 StartPosition CenterScreen Label Name lblquote Quote Font 26, Bold Location 160,8 GroupBox Name grpproduct Product Size 136,152 Location 0,56 CheckBox Name chka4paper (Draw inside grpproduct) A4 Blue Paper Location 8,24 Checkbox Name chkpaperclips (Draw inside grpproduct) Paper Clips Location 8,56 137

10 Object Property Setting Checkbox Name chkstaples (Draw inside grpproduct) Staples Location 8,88 Checkbox Name chkcalendar (Draw inside grpproduct) Calendar Location 8,120 GroupBox Name grpprice Price Size 80,152 Location 136,56 Label Name lbla4paper (Draw inside grpprice) 2.99 Location 20,29 Label Name lblpaperclips (Draw inside grpprice) 1.99 Location 20,61 Label Name lblstaples (Draw inside grpprice) 4.99 Location 20,93 Label Name lblcalendar (Draw inside grpprice) 7.99 Location 20,125 GroupBox Name grpquantity Quantity Size 88,152 Location 216,56 Box Name txtqtya4paper (Draw inside grpquantity) Size 72,20 Location 8,24 Align Right TabIndex 0 Box Name txtqtypaperclips (Draw inside grpquantity) Size 72,20 Location 8,56 Align Right TabIndex 1 138

11 Object Property Setting Box Name txtqtystaples (Draw inside grpquantity) Size 72,20 Location 8,88 Align Right TabIndex 2 Box Name txtqtycalendar (Draw inside grpquantity) Size 72,20 Location 8,120 Align Right TabIndex 3 Label Name lblpassword Password Location 0,248 Box Name txtpassword PasswordChar * Size 88,20 Location 64,248 Button Name btncalculate Calculate Size 88,32 Location 392,48 Button Name btnexit Exit Size 88,32 Location 392,80 Label Name lblsubtotal Sub Total Location 320,192 Label Name lbltax Tax 17.5% Location 320,224 Label Name lbltotal Total Location 320,256 Font Bold 139

Object Property Setting Box Name txtcalcsubtotal Align Right Size 90,20 Location 392,184 Box Name txtcalctax Align Right Size 90,20 Location 392,216 Box Name txtcalctotal Align Right

12 Object Property Setting Box Name txtcalcsubtotal Align Right Size 90,20 Location 392,184 Box Name txtcalctax Align Right Size 90,20 Location 392,216 Box Name txtcalctotal Align Right Font 10, Bold Size 90,22 Location 392,248 When the program is started the following screen appears. Most of the controls are not visible until the password Test is entered correctly. 140

$Enter the following code for the frmquote_load() event function. private void frmquote_load() { //Move the focus to the txtpassword Box txtpassword.$

13 Enter the following code for the frmquote_load() event function. private void frmquote_load() { //Move the focus to the txtpassword Box txtpassword.select(); } Enter the following code for the txtpassword_changed() event function. private void txtpassword_changed() { int i,j; //Check that the user entered the password "Test" correctly if (txtpassword. == "Test") { //Change the background colour of the password text box txtpassword.backcolor = Color.Purple; //Refresh the text box otherwise the colour does not appear txtpassword.refresh(); //Do a loop within a loop to count for a delay so that //the colour can be seen for (i = 1; i <= 20000; i++) { for (j = 1; j <= 10000; j++); } //Make the password label and text box not visible txtpassword. = false; lblpassword. = false; //Make the other controls visible grpproduct. = true; grpquantity. = true; grpprice. = true; btncalculate. = true; btnexit. = true; lblsubtotal. = true; txtcalcsubtotal. = true; lbltax. = true; txtcalctax. = true; lbltotal. = true; txtcalctotal. = true; } } 141

14 Enter the following code for the btnexit_click() event function. private void btnexit_click() { Application.Exit(); } Enter the following code for the btncalculate_click() event function. private void btncalculate_click() { //Declare the prices and Tax rate as constants so //that they can be changed easily. float or double is the //data type used for numbers that contain decimal places const double PRICEA4PAPER = 2.99; const double PRICEPAPERCLIPS = 1.99; const double PRICESTAPLES = 4.99; const double PRICECALENDAR = 7.99; const double TAXRATE = 17.5; double SubTotal = 0, Tax, Total; string StrSubTotal, StrTax, StrTotal; if (chka4paper.checked == true && txtqtya4paper.!= "") { SubTotal = SubTotal + Convert.ToDouble(txtQtyA4Paper.) * PRICEA4PAPER; } if (chkpaperclips.checked == true && txtqtypaperclips.!= "") { SubTotal = SubTotal + Convert.ToDouble(txtQtyPaperClips.) * PRICEPAPERCLIPS; } if (chkstaples.checked == true && txtqtystaples.!= "") { SubTotal = SubTotal + Convert.ToDouble(txtQtyStaples.) * PRICESTAPLES; } if (chkcalendar.checked == true && txtqtycalendar.!= "") { SubTotal = SubTotal + Convert.ToDouble(txtQtyCalendar.) * PRICECALENDAR; } //Format the SubTotal, Tax and Total values to Fixed Point "F" //This will allow the value to be displayed as 2 decimal places StrSubTotal = SubTotal.ToString("F"); txtcalcsubtotal. = " " + StrSubTotal; Tax = SubTotal * TAXRATE / 100; StrTax = Tax.ToString("F"); txtcalctax. = " " + StrTax; Total = SubTotal + Tax; StrTotal = Total.ToString("F"); txtcalctotal. = " " + StrTotal + " "; } 142

15 A constant is declared with the keyword const. The value of a constant cannot be changed while is program is running. Values that may need to be changed at a later date should be declared as constants and not written directly in the code. Constants are normally in uppercase to distinguish them from variables. A constant declared outside of any function can be seen by all functions. A constant declared inside a function can only be seen by that function. Save the project. Run the program. Enter the password Test and note that the text of the password is hidden and displayed as asterisks. Select a check box and enter a number in the Quantity for that product. When you have selected all the products required click the Calculate button. The following screen shows Paper Clips selected with a Quantity of 10 entered. String formats String data which contains numeric data can be formatted so that it appears in a numeric format e.g. with decimal places or with a currency symbol. The following table shows the basic types of formatting that can be used. Format Result "D" or "d" Decimal - integers "C" or "c" Currency currency symbol and 2 decimal places "F" or "f" Fixed point 2 decimal places "P" or "p" Percentage percentage sign inserted at end of string 143

The code for the formatting of the totals for the QUOTE program could also be done using the Currency format "C" which would mean that the " " sign would not need to be inserted separately.

16 The code for the formatting of the totals for the QUOTE program could also be done using the Currency format "C" which would mean that the " " sign would not need to be inserted separately. The following code shows how the Currency format can be used for the same calculation. //Format the SubTotal, Tax and Total values to Currency "C" //This will allow the value to be displayed //with a currency symbol and with 2 decimal places StrSubTotal = SubTotal.ToString("C"); txtcalcsubtotal. = StrSubTotal; Tax = SubTotal * TAXRATE / 100; StrTax = Tax.ToString("C"); txtcalctax. = StrTax; Total = SubTotal + Tax; StrTotal = Total.ToString("C"); txtcalctotal. = StrTotal + " "; Console.WriteLine() method The Console.WriteLine method can be inserted in code to output the value in a variable to the Output window. This can help when debugging because you can track the value of a variable as the program is running. The Output window appears at the bottom of the screen when the program is running in the development environment. The following line of code will output SubTotal = and then the value in the SubTotal variable at this point in the code as shown in the following Output window. Console.WriteLine("SubTotal = {0}", SubTotal.ToString("F")); The output is formatted as Fixed point ("F") which displays with 2 decimal places. 144

17 Locate the EXE file The location of the EXE file depends on whether you have used the default directory to store your projects. The default directory for Visual C# Express Edition 2005 is Visual Studio The path from this top level directory is then \Projects\projectname\bin\Debug. The projectname.exe should be stored in this Debug directory. Note that there is also a Release directory at this level. The Debug directory contains the EXE file which has debug information included. This makes the EXE file a larger size. Normally once a program is completed and tested it is compiled without any debugging information and placed in the Release directory. You need a professional version of Visual C# to be able to create a Release version of the EXE which does not include the Debug information. The program can be run outside the development environment by locating the EXE file and double clicking on it. 145

18 Questions Using the QUOTE project: Create test data and calculate the expected results for the program. Test the program and compare the expected results to the actual results. Produce a screen print to show the result for a quote. Add a new button named btnclear and set the property to Clear. When the Clear button is clicked all the checkboxes must be deselected and all the text boxes (except the text box for the password) must be set to empty. 2. Create a new project, save the project as STUDENT and the form as FormSTUDENT.cs. Build the form from the following table. Object Property Setting Form Name frmstudent Student program BackColor light yellow Size 384,280 StartPosition CenterScreen Label Name lbltitle MARKS Font Bold, 14 Location 144,9 Label Name lblname Name Location 16,40 Label Name lblmaths Maths Location 16,80 Label Name lblit IT Location 16,120 Label Name lblfrench French Location 16,160 Label Name lblresult Result Location 16,

19 Object Property Setting Label Name lblpassword Password True Location 16,230 Box Name txtname TabIndex 1 Size 184,20 Location 112,40 Box Name txtmaths TabIndex 2 Align Right Size 72,20 Location 112,80 Box Name txtit TabIndex 3 Align Right Size 72,20 Location 112,120 Box Name txtfrench TabIndex 4 Align Right Size 72,20 Location 112,160 Box Name txtresult TabIndex 5 Align Right Size 72,20 Location 112,200 Box Name txtpassword PasswordChar * TabIndex 0 Size 80,20 Location 112,230 True Button Name btncalculate Calculate Size 80,40 Location 272,

20 Object Property Setting Button Name btnnext Next Size 80,40 Location 272,149 Add a MenuStrip control to the form. Create the following menu: File Exit Name mnufile mnuexit When the program starts running the form should appear as shown below. When the correct password is entered the label and text box for the password must be removed and the other controls must be made visible. The form should then appear as follows. 148

Write code for the mnuexit_click() event function to end the program. Write code for the btncalculate_click() event function to work out the average of the marks for Maths, IT and French.

21 Write code for the mnuexit_click() event function to end the program. Write code for the btncalculate_click() event function to work out the average of the marks for Maths, IT and French. A result should be calculated as follows: If the average is less than 40 then the result is Fail If the average is between 40 and 64 (inclusive) then the result is Pass If the average is between 65 and 84 (inclusive) then the result is Merit If the average is 85 or more then the result is Distinction Write code for the btnnext_click() event function to clear the text boxes. Add try catch as appropriate. Create test data and calculate the expected results for the program. Test the program and compare the expected results to the actual result. 149

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Creating a procedural computer program using COBOL Level 2 Notes for City & Guilds 7540 Unit 005

Creating a procedural computer program using COBOL Level 2 Notes for City & Guilds 7540 Unit 005 Compatible with Micro Focus Net Express 5.0 COBOL compiler Version 1 Tench Computing Ltd Pines Glendale