CODEWITHSUNDEEP
c#vb.netintegerboolean
Jared.Rodgers
Jared.Rodgers

Reputation: 141

Checking if a Bool is Equal to an Integer

Ok, so I'm working for a company and before I was hired the company had a guy writing a program in Visual Basic. However, he got mad and ran off so I cannot communicate with him. My job is to convert his program to C#. He has no formal programming training so there are no comments in his code at all. In his code he has the following line (Written in C#):

if (boolVariable == 13)

I'm assuming I should just convert the int to bool or vice versa, but I figured I would ask you guys first. To give you more information, the boolVariable is only referenced in two other places. The declaration where it is being set to false, and in another if statement checking if it is true. No where else in the code is it being defined to something else, so I'm think that this just might be useless code. However, this piece of code does not cause an error in Visual Basics which also has me a little confused. Does visual basics automatically convert it for you? Any help will be greatly appreciated.

Upvotes: 0

Views: 1599

Answers (4)

Rufus L
Rufus L

Reputation: 37020

Yes, Visual Basic will convert it for you. Zero will be converted to False, and all other integers will be converted to True.

The simplest way to 'convert' the code you posted is to remove the '== 13'. This should accomplish the same thing.

if (boolVariable)
{ 
    // Do stuff 
}

But really the best thing to do would be to understand what logic is taking place:

  • What code gets executed in the block below when boolVariable is true?
  • What events trigger a change in the value of boolVariable?
  • What does boolVariable really represent (...and then change the name!)

If you can understand these things, then you can give the variable a more meaningful name (and possibly a more meaningful type), and the code will be easier to maintain in the future.

I don't envy you - it's a tough job converting bad, uncommented code. My advice is: don't just do a direct convertion. If you do that, then you just have bad, uncommented code in a different language. And a year from now we will see another post like yours about the code that you converted! :)

I would make sure your boss understands and signs off on the effort needed to do a decent conversion first, then spend the extra time to get it right.

Upvotes: 3

Karl Stephen
Karl Stephen

Reputation: 1140

VB behaviour :

You said it was written in VB, so, I assume that the original code looks like this :

    If boolVariable = 13 Then // Remeber : it was VB..
        // Code block if True
        // ...
    Else
        // Code block if False
        // ...
    End If

Now let's take a look at how the code will behave...

    // Remeber : it was VB..

    If boolVariable = 13 Then
    /* The boolVariable is a Boolean
    The "13" is an Integer
    First step is performing a Widening conversion Boolean -> Integer
    boolVariable is converted to 0 if False, or 1 if True.

    So, depending on the value of boolVariable, the statement is
    either : */
    If 0 = 13 Then // which is False
    // either :
    If 1 = 13 Then // which is also False

    // That means that writing If boolVarialbe = 13 is the same as writing :
    If False Then
        // Block of code THAT WILL NEVER BE EXECUTED
    Else
        // Block of code that will ALWAYS be executed
    End If

So IMHO, it doesn't make sense writing If (boolVariable == 13) (wether it's VB or C#)

I'm doing such weird things when I'm testing something specific that has nothing to do in the final code. Maybe the former programmer made something similar and failed to delete that part of the code. Without knowing what the code does and what its impact on an overall scope, I can't say if it's a critical part of the application that should be fixed, or garbage.

Anyway, such statements like If (boolVar == numVar) are a no-go in today ways of programming (IMHO) The former programmer failed to activate Option Strict which would have prevented him from writing it.

Upvotes: 0

Rotem Varon
Rotem Varon

Reputation: 1647

I am not pretending to be an expert in VB but here is a working example:

Imports System

Public Class Test
    Public Shared Sub Main()
        Dim runningVB As Boolean
        ' Check to see if program is running on Visual Basic engine.
        If scriptEngine = "VB" Then
            runningVB = 16
            If runningVB = True Then
                Console.WriteLine("True")
            End If
            runningVB = 0
            If runningVB = False Then
                Console.WriteLine("False")
            End If
        End If
    End Sub
End Class

With the output:

True
False

So, like many other programming languages, false will be for Zero and true otherwise. Even though this type of checking is perfectly acceptable in C, the C# compiler probably will complain.

Upvotes: 4

Rose
Rose

Reputation: 641

maybe the sample code below will help.. ;-)

Option Strict Off  ' this code will not compile with (Option Strict On)
Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        Dim boolVariable As Boolean = False

        boolVariable = -1   ' anything non-zero will set boolean to True
        Debug.WriteLine(boolVariable)
        boolVariable = 0    ' zero will set boolean to False
        Debug.WriteLine(boolVariable)
    End Sub
End Class

Upvotes: 0

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