Visual basic intro, Slides of Computer Networks

Download Visual basic intro and more Slides Computer Networks in PDF only on Docsity! Introduction To Visual Basic 6 Programming language  Programming is writing instructions for a computer.  Level of programming languages  Machine language – 0s and 1s  Intermediate languatge – assambly language.  High level language – BASIC, C++… Why do we learn Visual Basic  It shares the same principles with other programming languages.  It is good when developing small and handy utility programs.  It is supported by Microsoft.  It is powerful when integrated with Excel and Word. Six Steps in Programming  Problem Identification  Solution Design  Coding  Compiling with compiler or running with interpreter  Debugging  Testing Step 1 and 2: Problem Identification and Design  Identify what needs to be solved  Make diagrams, and equations, etc  Design: Analyze the problem and develop an ALGORITHM and FLOWCHART Step 4b: Interpreting  Interpreting reads and runs one line of code each time.  You can find “Grammar errors” in this stage.  Advantage:  Good for debugging  Interpreter is easy to program.  Disadvantage:  Slow Interpreting and Compiling in VB |s-ia- Boe | h = & Pst FS Start With Eull Compile Ctrl+F5 |] Break Ctl+8reak wi End Restart shift  Step 5: Debugging  Debugging is removing the “functional errors” from your program  Running tells you where there are errors  Go back to source code and fix errors  Save and re-run  Repeat until errors are gone VB programming Project Form 1 Form 2 Form 3 Text box Button Picture box Objects Text box Button Objects Definitions  Form contains the Main Program  Controls are user interface elements (text boxes, commands) in the Form  Forms and Controls are referred to as OBJECTS  Objects have PROPERTIES (features you can change) Forms in Visual Basic  You create a form that is your graphical user interface  Has places to input values  Has buttons to click  Has other user interface elements, e.g. Menu, scroll bar… Important Controls  Text Boxes – area where you enter text  Command Buttons – you click on them to do something  Picture Boxes – Output your results. Text Boxes  Properties:  Name (of object)  Text (the words)  Alignment (left, right, middle)  Appearance  BackColor (background)  BorderStyle  Font  FontColor Command Button  Properties:  Name  BackColor  Style (This controls the backcolor)  Caption “Design time” and “Run time”  When you design you can use the property window to set the property of certain object.  When you run the program, you can only use code to change the property of that object. Just a Bunch of Objects  Q: Now that you have a bunch of objects, how do you make them react to your command?  A: Sub Procedures  Sub Procedures are the instructions  Sub Procedures go with Events (Like clicking a button) How the test program works © ~ Ch rlsllo ores yo x]  Sub Procedure  Two Objects: Text1 and Command1 Sub Procedure: Private Sub Command1_Click() Text1.FontSize = 18 End Sub  When Command1 is clicked, the FontSize property of Text1 is changed to 18 Sub Procedure Private Sub CommButt_Click() Text1.FontSize = 18 Text1.BackColor = vbBlue Command1.Caption = "Get Some Now" End Sub Homework O Read Chapters 1 & 2 in book