Vb Net Lab Programs For Bca Students Fix -

Objective: Create a base class Employee with name, ID, and basic salary. Derive Manager and Developer classes that override a CalculateBonus() method.

Concepts: Inherits keyword, Overridable / Overrides, polymorphism.

Learning Outcome: Understanding code reusability and runtime polymorphism.

| Symptom | Most Likely Fix | |---------|----------------| | "Object reference not set to an instance of an object" | You used a control or array before New or assignment. | | "Conversion from string to type 'Double' is not valid" | Textbox contains letters or is empty. Use TryParse. | | Form runs but nothing happens on button click | Missing Handles Button1.Click. | | Infinite loop | Loop condition never becomes false. Add Step or i += 1. | | Output is always zero or default | Variable scope issue – declared inside a block but used outside. | vb net lab programs for bca students fix

Sometimes there is no red squiggly line. The program runs, but gives the wrong output. Here is how to fix logic errors.

Visual Basic .NET (VB.NET) is an object-oriented programming language implemented on the .NET Framework. For BCA students, it is crucial to understand that VB.NET is not just a simple scripting language; it is a fully object-oriented language that supports inheritance, polymorphism, and exception handling.

This is a critical topic for BCA final projects. Objective : Create a base class Employee with

Time: 3 Hours | Max Marks: 50

Question 1 (10 Marks): Design a VB.NET application to calculate the area of a circle, rectangle, and triangle using radio buttons and a single compute button. Implement appropriate input validation.

Question 2 (15 Marks): Create a LibraryBook class with properties (BookID, Title, Author, IsIssued). Write methods to issue and return books. On a Windows Form, display books in a ListBox and update status. | Symptom | Most Likely Fix | |---------|----------------|

Question 3 (15 Marks): Develop a simple billing system for a grocery store. Use a DataGridView to add items, compute total bill, apply discount (5% if total > 1000), and display final amount.

Question 4 (10 Marks): Write a VB.NET program that reads a text file (notes.txt), counts the number of words, lines, and characters, and displays the result in a multiline textbox. Handle file-not-found exception gracefully.

Print this checklist and keep it with you during your BCA practical exam.

Testing: Corrupt file handling, schema changes.