Visual Basic Interview Questions for Developers

Use our engineer-created questions to interview and hire the most qualified Visual Basic developers for your organization.

Visual Basic

While Visual Basic may have been superseded in use by more modern programming languages in most enterprises, this Microsoft-developed language still has a heavy presence in many legacy applications and remains great for Rapid Application Development (RAD) and its low learning curve.

Created in 1991, Microsoft updated the language in 2002 to be a part of the .NET framework, naming the new version VB.NET.

We have created functional coding tasks and interview queries specifically designed to assess developers’ Visual Basic abilities during coding interviews. In addition, we have gathered a collection of best practices to guarantee that your interview questions effectively measure the candidates’ expertise in Visual Basic.

Visual Basic example question

Help us design a parking lot

Hey candidate! Welcome to your interview. Boilerplate is provided. Feel free to change the code as you see fit. To run the code at any time, please hit the run button located in the top left corner.

Goals: Design a parking lot using object-oriented principles

Here are a few methods that you should be able to run:

  • Tell us how many spots are remaining
  • Tell us how many total spots are in the parking lot
  • Tell us when the parking lot is full
  • Tell us when the parking lot is empty
  • Tell us when certain spots are full e.g. when all motorcycle spots are taken
  • Tell us how many spots vans are taking up

Assumptions:

  • The parking lot can hold motorcycles, cars and vans
  • The parking lot has motorcycle spots, car spots and large spots
  • A motorcycle can park in any spot
  • A car can park in a single compact spot, or a regular spot
  • A van can park, but it will take up 3 regular spots
  • These are just a few assumptions. Feel free to ask your interviewer about more assumptions as needed

Junior Visual Basic interview questions

Question: Explain the concept of Object-Oriented Programming (OOP) in Visual Basic, and provide an example of a class with its properties and methods.

Answer: Object-Oriented Programming (OOP) in Visual Basic is a programming paradigm that focuses on creating classes and objects to model real-world entities and their interactions. Classes are blueprint templates that define the structure and behavior of objects. Objects, on the other hand, are instances of classes that encapsulate data (properties) and behavior (methods).

Here’s an example of a class in Visual Basic:

Public Class Car
    ' Properties
    Public Make As String
    Public Model As String
    Public Year As Integer
    Public Speed As Integer

' Methods
    Public Sub Accelerate()
        Speed += 10
    End Sub

Public Sub Brake()
        If Speed >= 10 Then
            Speed -= 10
        Else
            Speed = 0
        End If
    End Sub
End Class

In this example, we have defined a Car class with properties Make, Model, Year, and Speed. The class also contains two methods, Accelerate() and Brake(), which modify the Speed property based on the car’s actions.

Question: The following Visual Basic code is intended to calculate the factorial of a given number. However, it contains a syntax error and doesn’t produce the correct result. Identify the error and fix the code.

Function Factorial(ByVal n As Integer) As Integer
    If n = 0 Then
        Return 1
    Else
        Return n * Factorial(n - 1)
    End If
End Function

Answer: The code for calculating the factorial is almost correct, but it is missing the base case for negative numbers. To fix the code and handle negative input correctly, we can add a condition to check for negative values.

Function Factorial(ByVal n As Integer) As Integer
    If n < 0 Then
        Throw New ArgumentException("Factorial is not defined for negative numbers.")
    ElseIf n = 0 Then
        Return 1
    Else
        Return n * Factorial(n - 1)
    End If
End Function

In this corrected code, if the input n is negative, the function throws an ArgumentException with an error message. For non-negative inputs, the function correctly calculates the factorial using recursion.

Question: Explain the difference between ByVal and ByRef in Visual Basic when passing arguments to functions or procedures.

Answer: In Visual Basic, ByVal and ByRef are used to specify how arguments are passed to functions or procedures.

  • ByVal: When using ByVal, the value of the argument is passed to the function or procedure. Any modifications made to the argument within the function or procedure do not affect the original value outside the function or procedure.
  • ByRef: When using ByRef, a reference to the memory location of the argument is passed to the function or procedure. Any modifications made to the argument within the function or procedure affect the original value outside the function or procedure.

Here’s an example to illustrate the difference:

Sub Example(ByVal x As Integer, ByRef y As Integer)
    x = x + 1  ' Changes to x do not affect the original variable.
    y = y + 1  ' Changes to y affect the original variable.
End Sub

Sub Main()
    Dim a As Integer = 5
    Dim b As Integer = 10

Example(a, b)

Console.WriteLine("a: " & a)  ' Output: a: 5
    Console.WriteLine("b: " & b)  ' Output: b: 11
End Sub

In this example, the value of a remains unchanged after calling the Example subroutine because ByVal is used. However, the value of b is modified after calling the Example subroutine because ByRef is used.

Question: The following Visual Basic code is intended to check if a given number is a prime number. However, it contains a logical error and doesn’t produce the correct result. Identify the error and fix the code.

Function IsPrime(ByVal num As Integer) As Boolean
    For i As Integer = 2 To num - 1
        If num Mod i = 0 Then
            Return False
        End If
    Next
    Return True
End Function

Answer: The code is almost correct, but it has a logical error in the loop termination condition. The loop should check up to the square root of num instead of num - 1. Additionally, the function should return False for input values less than or equal to 1, as they are not prime numbers.

Here’s the corrected code:

Function IsPrime(ByVal num As Integer) As Boolean
    If num <= 1 Then
        Return False
    End If

For i As Integer = 2 To Math.Sqrt(num)
        If num Mod i = 0 Then
            Return False
        End If
    Next
    Return True
End Function

In this corrected code, we first handle the special cases where num is less than or equal to 1, and then the loop iterates up to the square root of num to efficiently check for prime factors.

Best interview practices for Visual Basic roles

To carry out successful Visual Basic interviews, it is crucial to take into account various aspects, such as the applicant’s background and the specific engineering position. For a productive interview experience, we suggest implementing the following best practices:

  • Create technical questions that represent real-life business situations within your organization. This method will effectively engage the applicant and help assess their fit with your team.
  • Foster a collaborative atmosphere by encouraging applicants to ask questions throughout the interview.
  • If you’re using Visual Basic for object-oriented programming, make sure your candidates have an understanding of OOP concepts like inheritance and polymorphism.

Following established interview procedures is vital when conducting Visual Basic interviews. This includes tailoring the complexity of the questions to suit the applicants’ skills, promptly updating them on their application status, and giving them the chance to inquire about the evaluation process and working with you and your team.