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Visual Basic Quickstart Guide

You're reading from   Visual Basic Quickstart Guide Improve your programming skills and design applications that range from basic utilities to complex software

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Product type Paperback
Published in Oct 2023
Publisher Packt
ISBN-13 9781805125310
Length 238 pages
Edition 1st Edition
Languages
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Author (1):
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Aspen Olmsted Aspen Olmsted
Author Profile Icon Aspen Olmsted
Aspen Olmsted
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Table of Contents (27) Chapters Close

Preface 1. Part 1:Visual Basic Programming and Scripting FREE CHAPTER
2. Chapter 1: The Visual Basic Family of Programming Languages 3. Chapter 2: Console Input and Output 4. Chapter 3: Data Types and Variables 5. Chapter 4: Decision Branching 6. Chapter 5: Iteration 7. Chapter 6: Functions and Procedures 8. Chapter 7: Project Part I 9. Part 2:Visual Basic Files and Data Structures
10. Chapter 8: Formatting and Modifying Data 11. Chapter 9: File Input and Output 12. Chapter 10: Collections 13. Chapter 11: Project Part II 14. Part 3:Object-Oriented Visual Basic
15. Chapter 12: Object-Oriented Programming 16. Chapter 13: Inheritance 17. Chapter 14: Polymorphism 18. Chapter 15: Interfaces 19. Chapter 16: Project Part III 20. Part 4:Server-Side Development
21. Chapter 17: The Request and Response Model 22. Chapter 18: Variable Scope and Concurrency 23. Chapter 19: Project Part IV 24. Chapter 20: Conclusions 25. Index 26. Other Books You May Enjoy

Building the project in VB6

We will now build Visual Basic 6 code for a simple calculator program. The program has a form that loads when the application starts. The form contains a loop that prompts the user to input two numbers and an operator and then operates on the two numbers. The loop prompts the user until they enter X to quit. Finally, the program displays the result of the operation in a message box. For example, if the user tries to divide by zero, a message box says, "Cannot divide by zero!". The program uses the Cint function to convert the inputted numbers into integers and handles errors using message boxes:

Private Sub Form_Load()
  Dim n1, n2, res, operator, sentinel As String
  sentinel = False
  Do
    n1 = InputBox("Enter the first number or X to quit:")
    If n1 = "X" Then
        sentinel = True
    ...
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