CODEWITHSUNDEEP
vb.netlogical-operatorscomparison-operators
AgentRev
AgentRev

Reputation: 809

Confused with conditional and logical operators - VB.net

I'm kind of new to VB.net, and since I just finished a C# course, the lack of parentheses creates a lot of confusion on how to write certain combinations of operators.

The C# equivalent of the line I am trying to reproduce in VB would be like this :

if ( (a == 0 && b != null) || (a == 1 && c != null) )

I'm have no idea how to write this in VB, I've tried many combinations of And, Or, AndAlso, OrElse, etc. but I can't achieve the desired result.

I can't find any clear example of C# v.s. VB.net comparison on operators, and the notes I have aren't helpful either.

Can someone help me figure this out?

Upvotes: 2

Views: 9199

Answers (3)

Olivier Jacot-Descombes
Olivier Jacot-Descombes

Reputation: 112392

The equals operator is == in C# and = in VB.

if ( (a == 0 && b != null) || (a == 1 && c != null) )
    statement; // One single statement only

or

if ( (a == 0 && b != null) || (a == 1 && c != null) ) {
    statement; // Any number of statements
}

This online conversion tool will convert it to VB for you:

If (a = 0 AndAlso b IsNot Nothing) OrElse (a = 1 AndAlso c IsNot Nothing) Then
    statement
End If

C# && translates to AndAlso in VB.
C# || translates to OrElse in VB.

With these operators the evaluation stops as soon as the result is determined. This is known as "short-circuit" evaluation. E.g. in a && b the result is known to be false if a is false, and b will not be evaluated. This is especially important when the evaluation has side effects, like performing database queries, raising events or modifying data. It is also useful in conditions like these person != null && person.Name == "Doe" where the second would throw an exception if the first term evaluates to false.

The equivalent of the VB And and Or Boolean operators that do not use short-circuit evaluation are & and | in C#. Here all the terms will always be evaluated.

If (a = 0 Or b = 0 And c = 0) Then
    statement
End If

if (a = 0 | b = 0 & c = 0) {
    statement;
}

Upvotes: 5

Bala R
Bala R

Reputation: 108957

The vb.net equivalent would be

If (a = 0 AndAlso b IsNot Nothing) OrElse (a = 1 AndAlso c IsNot Nothing ) Then

Note in c#, it should be a == 0 and not a = 0

Checkout this post with a comprehensive comparison.

Upvotes: 4

keithwill
keithwill

Reputation: 2044

if ( (a = 0 && b != null) || (a = 1 && c != null) )

Is equivilent to:

if ( ( a = 0 AndAlso b IsNot Nothing) OrElse (a = 1 AndAlso c IsNot Nothing) )

Upvotes: 0

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