Use the MsgBox function to indicate the problem to the user. If Val txtTwo. SetFocus The SetFocus method returns the cursor to the first input box. Set properties to pretty it up. Check that it works. Use integers, very big numbers, very small numbers, negative numbers, zeros, etc. Is your label big enough for all values? Connect to a Binary Selection menu heading on the main form.
Sequence algorithms The programs in Activities 1 — 3 were all constructed from sequence algorithm constructs. Each line of code followed another with only one possible pathway for each event. So, for each sub procedure, the algorithm would consist of input, output and a series of process steps, e.
Selection allows multiple pathways for any event and allows for choices to be made. Here is the syntax in Visual Basic. Enter the measurement The measurement in centimetres is 2. Option buttons are mutually exclusive, i. Try it out with some test data including very large numbers, very small numbers, zero, negative numbers, 0.
Multiway selection In Activity 5 we looked at an example of binary selection. If the selection involves more than two alternatives, you can use nested If statements but this becomes complicated and leads to hard-to-read code.
It is better to use Case statements. Here is the syntax for multiple selection through Case statements. The post office has the following charges for parcels based upon different weights. Use Case statements in your code. Link this as CaseWeights under the Multiway menu heading in your main form. Use a set of check boxes to allow a user to choose the noise level by the comments, then output the probable decibel level based on information in the following table.
Activity 7 A control array is a set of multiple controls of the same type with the same name often created by using the Copy and Paste command. You may have encountered this already in adding radio buttons or check boxes to your form. Individual controls within the array are distinguished by having different Index property values. Try this out, then add code to change the label background colour to something appropriate for each different day. Before we continue with the last structures — iterations — check that the menu headings on Main are all correct and linked by code to the correct forms.
Check the list below and change any that need to be changed. Each iteration MUST contain a way of stopping the looping. Activity 8 Create a new form and link to iteration — pre-test - Count the beeps on the Main menu. Add a text box and a command button. Put a label above the text box asking the user to input a number between 1 and If the number is valid, use Do While …… Loop to issue that number of beeps. Name your form frmBeeper.
Then write the pseudocode algorithm for this program. Activity 9 In this tutorial, we look at writing code containing the 5 basic control structures. Open a new form and create a link to the program from the menu form Main under Iterations … Post-test Loops … Averages. Write an application to display the average of 10 numbers entered by the user using a post-test loop with the syntax Do …..
Loop Until to ask for each number. Multiple document Interface: The MDI was designed to simplify the exchange of information among documents, all under the same roof. With a MDI application, you can maintain multiple windows, but not multiple copies of the application.
Data exchange is easier when you can view and compare many documents simultaneously. The main form or MDI form is not duplicated, but it acts as a container for all the windows, and it is called the parent window. A MDI application must have at least two forms, the parent form and one or more child forms.
There can be many child forms, but only one parent form. He parent form may not contain controls. While the parent form is open in the design mode, though the icons in the toolbox are not disabled, but you cannot place any control on the form.
But you can place controls in child forms. To create a MDI application follow these steps: 1. Make this form child by setting its MDIChild property true. To denote that this is a child form set its caption to MDIChild. Double-click your picture control in the tool box. It will appear as toolbar to your MDI form. Place three command buttons on this toolbar and change their names and captions to newchild, cascade and tile respectively.
The MDI window will look as in the below. Enter the codes as shown in the below. Save and run the project. See how you can arrange the child windows in tiles or cascades. You cannadd any number of child windows by clicking the newchild button. A typical tile arrangement of child windows is shown in the below and cascade arrangement of the child windows in the below.
To create an MDI application 1. Create an MDI form. Note An application can have only one MDI form. If no code in these QueryUnload event procedures cancels the Unload event, then each child is unloaded, and finally the MDI form is unloaded.
Because the QueryUnload event is invoked before a form is unloaded, you can give the user the opportunity to save a form before unloading it. Features of MDI Form?
In order to display as many documents as the user wants, your application will have to replicate itself as many times. If this were possible, imagine the number of controls, and the code that would have to be loaded in memory.
There must be a more practical and efficient way to solve this problem. It is in the form of the Multiple Document Interface MDI 1 An MDI application allows the user to display multiple documents at the same time, with each document displayed in its own window.
Documents or child windows are contained in a parent window, which provides a workspace for all the child windows in the application. The user can start an application, minimize it and close it with a single control , need not close all the Forms.
After all functions like adding, displaying, sorting records, etc. Common controls can be available with the MDI form and share by the other forms. Building User Interface The principles of design that is applicable in most interactive systems. These underlying principles of interface design Consistency:- Visual Basic offers a host of controls, However, do not make the mistake of using all of them.
A number of controls can be used to do the same job. For a particular task have to use the particular control only. Fonts :- The fonts are another area where the designer might run away with his imagination.
Simplicity :- Make sure that the interface you present to the user is simple and easy to use. The interface is the place where you show a concern for the user who is not as knowledgeable about computers as you are.
It must be based on the thought pattern of an Average user. Try and think how the target user will accomplish this job. Provide clues where required without making an overkill.
Usability :- The user must be able to use your application with ease. The user is also concerned with the help ,hints and guidance he can get from the applications itself. Images :- A picture is worth a thousand words. Your understanding of the theme will depend upon your frame of mind at the time. That is the problem of using images or icons to convey a message.
Use only those pictures and icons in your program that are universally understood and accepted. What you understand may not be what the user does. Colors :- Use Simple colors. The user is going to be looking at the form that you have designed. Do not have too many colors on your form. When viewed on a color display, some of the colors may disappear. Compile Time Errors 2. Runtime Errors 3. Logic Errors 1. Compile Time Errors: These Errors occurs while writing the code.
They usually occur when the syntax of any visual basic statement is invalid. These Errors are easy to locate and correct. VB checks the syntax of each line of code as you enter and informs you by means of highlighted text.
They do not occur until you run your application. Logic Errors: Logical Errors occur when your application produces in correct results. These errors normally occur due to a mistake made by the programmers. Error Description Syntax Error Occurs when we enter an incorrect line of code such as a mistake in typing a keyword, a punctuation is missing or an incorrectly spelled variable.
For example, using an If statement without a matching End If results in a syntax error. Visual Basic notifies us of the syntax errors before we leave a line of code. Run-time Error Occurs when a command attempts to perform an action that is not valid. For example, a run-time error occurs if we try to assign a string to a numeric variable.
Error handlers execute only if a run-time error is encountered. Logic Errors Occurs when an application executes without syntax errors or run-time errors, but the results are not what we intend. For example, an application might prompt the user for a password but then may not allow access to the application even if the password is correct. This might be acceptable during development and testing phases. So, your code should trap and deal with its own errors.
This statement waits for an error to occur and when the error occurs the error trap statement performs an action written under error handler. On error statement has three forms. On Error Goto Label 2. On Error Resumenext 3. On Error Goto 1. On Error Goto Label : using this statement in your code, makes VB application to jump to a specific location in your code, if an Error occurs.
Errors handle code is always written at the end of the procedure. This is because in the code, If no error occurs, you must exit the procedure, before reaching the error handler. Otherwise VB executes Error Handling code. On Error Resume Next : It tells VB application to suppress the standard error message and simply execute the next line of code.
If the file exist the kill procedure deletes it. But, it is suppressed due to an error resume next statement and procedure terminates normally. This has a number of properties. The most important properties are number and description. Property Description Number Returns or sets a numeric value specifying an error. We use the Number property to determine which error occurred.
The value of the property is a unique number that corresponds to the error condition. Syntax: Object. Number Description Returns or sets an expression containing a descriptive string associated with an error. ActiveX Components. But some Objects in windows environment are not unique to Visual Basic and they do not come with visual basic language.
So, other applications provide these Objects and use them with in you applications. OLE Enables to access the functionality of multiple applications, with in single programming environment.
OLE is not a programming technique but it is a technology provided only in windows environment. OLE Terminology: 1. A Component is an Item a control or an application that some one else has developed. Compound Document: A document that contains more than a single type of Object is called a Compound Document.
Container Application : An application that contains Linked or Embedded Objects is an container application. Object Embedding: with this technique you can insert an Object from one application into another application.
Object Linking: This technique is similar to Object Embedding except that the changes made to the Object Word or Excel in the server are reflected automatically in the container application. By selecting the Object through insert Object dialog box. Embedding with Drag and Drop : 1.
Immediately insert dialog box appears chick on cancel button. Since we are Embedding Object using Drag and Drop. Start an application that supports OLE and open a file. In this exaple, we will start Microsoft Word application and insert a Word Document in the OLE container control by dragging and dropping the document Copy and paste.
You can edit it with words Menus and Tool Bars. Linking and Embedding with insert Object Dialog Box: 1. Immediately insert Object Dialog Box appears. From that Dialog Box select the option create from file option button and check the Check Box.
Click on the browse button to locate the file you want to Embed. Immediately the selected file appears on the OLE container control. ActiveX : What is ActiveX? ActiveX is a reusable and portable software component or control built according to what are called COM Component Object Model specifications. It is the brainchild of Microsoft. It provides a building block solution to complex problems. Visual Basic ActiveX Controls: When you start VB, the first window called the design window shows some 20 intrinsic controls like label, command button, option button etc.
These controls cannot be removed from the Toolbox. These controls can be added to or removed from the Toolbox. You will get the New Project Menu as shown in the figure 1. When you move the mouse pointer over the icon, the names of the controls will appear below them.
The Components Dialog Box will appear on the screen as shown in the figure 3. Select the required control by clicking on the rectangular box at the beginning. After selecting the required controls, click OK. The icons of the selected controls will now appear on the Tool box and you can use them just as you will use any other intrinsic ActiveX control. This is in addition to the intrinsic controls already introduced in earlier versions.
The Common Dialog Control enables the users to create Dialog Boxes open, save, print, setup, font, help and so on in their own applications. The Animation Control enables the users to play silent avi files producing animation appropriate to the operations performed. The Communication Control describes how to use it with a modem to dial a phone number, interact with another modem or add advanced communication functionality to your applications.
The ListView Control enables the users to organize and view the data in deifferent ways using the View Property. The MAPI Control enables the users to sign-on to an electronic messaging system, access an Inbox, send or receive messages or send file attachments. The Masked -Edit Control enables the users to create mask platforms that prompt them for date, time currency or customized data input.
The MSChart Control enables users to create barchrts, assign and edit backdrops and load data from an array. The Multimedia Control enables the users to control and manage t5he recording playback of a variety of multimedia using a simple push-button interface.
The ProgressBar Control enables the users to get a feedback about a lengthy operation by pictorially displaying a moving coloured bar. The Slider Control enables the users to select a range of data between a maximum and a minimum setting.
The Sysinfo Control enables the users to determine the current operating system, how to monitor and respond to Plug and Play events or changes in AC and battery power status. The Tabbed Dialog Control enables the users to present several dialogs or screens of information on a single form using the same interface. The TabStrip Control enables the users to create tabs by adding tab objects to the tab collection.
Use an imagelist controlo to supply bitmaps for the tabs. This project requires a timer and two labels. The running time will be displayed in one label and the current date will be displayed in the other label. Drag one timer and two label controls into the form. Give the labels appropriate size, font and border and set their caption property blank.
Set the timer interval property as one second and the Enabled property as True. The project at the design time looks as in the below. Entering the Event Codes: Open the code window by double clicking the Timer control and enter the code as shown in the figure 4a. The clock will begin to run.
The current date will be displayed in the other label. The run mode window is as shown in the figure 5. Another important point you notice is that the timer control does not appear in the run mode, and is invisible, but works only from behind.
RichTextBox Control allows the user to enter text with varying fonts and sizes. Set the command button caption and name as font. A font dialog box can be opened only through the Common Dialog control. The Common Dialog control box will be invisible during run time. Save the form and the project. Enter the codes as shown in the below and finally save the project. ShowFont RichTextBox1. FontName RichTextBox1. FontSize RichTextBox1. FontBold RichTextBox1.
FontItalic RichTextBox1. You type any text in the RichTextBox and select it. Click the font button. The font dialog box will open. Set the desired font and size. On deselecting the text, you will find the text printed in the desired font and size.
This includes a set of activities. These activities are 1. Preliminary Investigation 2. Determination of System Requirements 3. Design the System 4. Development of Software 5. System Testing 6. Implementation and Maintenance. Preliminary Investigation : This activity has 3 parts.
Request Classification 2. Feasibility Study 3. So, the project request must be examined to determine what the organizer wants? Feasibility Study: This activity determines whether the study requested is feasible or not. There are 3 aspects in feasibility study i Technical Feasibility : can the project be done with current equipment, available persons and with existing software.
Request Approval: Not all requested projects are feasible and desirable. So, the projects that are feasible and desirable must be put in to schedule.
Determination of System of Requirements : Analysis working closely with Employees and Managers must answer these question to determine the system requirements. What is being done? How is being done?
How frequently does it occur? How well the task is being performed? To answer these questions systems analyst take to a verify of persons. Design to the System: The system design describes the data to be input, the data to be output and the procedures. This information is passed to programming staff. So, that software development can begin, Designers are responsible for providing complete and clear information about the system to programmers.
Development of Software: For the development of new system software developers install newly purchased software. System Testing: During system testing the system is used experimentally to test whether the system is according to the requirements. In this activity input is given to the system and the results are examined. Implementation and Maintenance : Implementation is the process of checking the system have to be maintained that is modifications and changes will be made to the software to meet the new requirements.
To draw such data flow diagrams, the different notations used are 1. Process : This represents people procedures or devices that use or procedure data. Source or Destination : This may be people, programs or any other Entities. Data Store : The data store represents data bases each Component in Data Flow Diagram is labeled with a descriptive name.
Data Flow Diagrams allows analysts to study how the data enter the process and how they are changed when they leave the process. If the analyst want to review the overall system hw uses higher level Data Flow Diagrams. If they are instructed in studying one particular process they use lower level Data Flow Diagrams. Using Data Flow Diagrams users can make suggestions for modifications more accurately. These are two types 1. Visual Basic has many built-in functions that are a part of the base language and may be called at any time from your procedures.
Cos ExpN This function returns the cosine of an angle angle in radians Sin ExpN This function Returns the sine of an angle angle in radians String Functions Len str This function returns the number of characters in a string expression Eg. Eg: Me. Minute Returns an integer between 0 and 59, inclusive, that represents the minute of the hour corresponding to the time provided as an argument Month Returns an integer between 1 and 12, inclusive, that represents the month of the year for a date argument.
Practice Application: Program. By clicking the Microsoft Visual Basic 6. Double Click on the Command1 Ok , a Code window will appears. After the completion of a code Save the Project with appropriate name and run the project by pressing the Function Key F5. The Output is Viewed as shown in figure.
Procedure: 1. Output: Program. In the Form Design the Calculator which is shown in the right side by using the related Controls. Double Click the Form , the Code Window will appears. Text End Sub 9. AddItem "Regular". AddItem "Bold". AddItem "Italic". FontCount List1. AddItem Screen. Fonts i Next End Sub 7. List Combo1. ListIndex Case "Regular" Text1. List List1. ListIndex End Sub 9. After completion of the Code, save the project with an appropriate name and run the project by clicking on the F5 Function Key.
Show End Sub 6. Show End Sub 7. AddItem Text1. Text End Sub RemoveItem List1. RemoveItem Combo1. After Completion of a Code, Save the project with an appropriate name and run the application by pressing F5 Function Key.
In the Form design 5 Labels and one rectangle , one combo box, one list box , one Horizontal scroll Bar. AddItem "Rectangle". AddItem "Square". AddItem "Oval". AddItem "Circle". AddItem "Rounded Rectangle". AddItem "Solid". AddItem "Transparent". AddItem "Horozontal Line". AddItem "Vertical Line". AddItem "Upward Diagonal". AddItem "Downward Diagonal". AddItem "Cross". ListIndex End Sub 8. In the Form design 3 Labels ,2 text boxes and one command button.
In the Form design 3 Labels ,2 text boxes 4. Burrows,Joseph D. Parents will discover the basic knowledge of teachers applied to assisting parents into being "good" teachers as parents. Knowledge utilized every day by teachers is transformed into a parenting tool that is essential and wonderfully easy to acquire. Parents will finally have the basic understanding to assist them in teaching their own children and the vocabulary necessary to discuss with teachers their child's needs.
Written by a teacher who is also a business woman, Teaching Parents It is formal cognitive thinking at the highest level. The authors and the publishers of this book are grateful to the readers for their overwhelming support for the earlier editions. In this edition, the readers of the book are introduced to the development of a small package for online test. Each chapter begins with objectives and a brief overview.
Numerous coding examples as well as small hands-on projects with thorough guidance appear throughout. Chapter Walks the reader through preliminaries of Visual Basic. Various elements of VB such as standard tool bar, form design window, form layout window are explained with ample screen shots. Chapter Takes the reader through the data types, naming conventions, operators, built in functions, and control constructs in an organized manner.
Chapter Explains standard controls such as frames, check boxes, option buttons, combo boxes, shapes, lines and timer in a systematic way.
Chapter Gleans through multiple forms, menus, MDI forms and control arrays in a methodical fashion. Chapter Covers standard code modules, image, picture box and custom controls with illustrative screen snapshots. Chapter Explores various drawing tools provided by VB. The potentials of Graphic methods have been clearly explained.
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