Why And is needed when there is AndAlso

Question

I have referred What is the difference between And and AndAlso in VB.net? to understand the difference between And and AndAlso.

I am from C# background - and C# has AndAlso only - no And.. And I don't see any practical use/advnatage of And.

Is there any practical use of And in VB.Net?

Reference

http://programmers.stackexchange.com/questions/227982/most-efficient-multiple-condition-if-statement — gnat, Jul 01 '14 at 12:50
AndAlso and OrElse are recent additions to VB.NET to cut down on the full evaluation of all of the clauses in a comparison. This addition brought VB.NET more in-line with C#'s comparison clauses. — Adam Zuckerman, Jul 01 '14 at 12:55
@AdamZuckerman What do you mean by "recent". In which version did get introduce? — LCJ, Jul 01 '14 at 12:59
I don't remember exactly when it was, but i seem to remember it being around the time Visual Studio 2008 was released. I have been writing for for over 25 years, so that seems recent to me. — Adam Zuckerman, Jul 01 '14 at 13:05
C# has both the short circuiting AndAlso in the form of && and the non short circuiting And in the form of &. — CodesInChaos, Jul 01 '14 at 17:01
Why did Visual Basic .NET introduce AndAlso and OrElse?: Prior to VB.NET, the VB language only had the And and Or operators. They were essentially bitwise operators, which means that they took their two operands and performed an AND or OR operation on each bit position to produce the resulting bit — phuclv, Apr 14 '18 at 13:26
@AdamZuckerman to be precise it was introduced in VB.NET 2002 as in the above link — phuclv, Apr 14 '18 at 13:27

score 5 · Accepted Answer · answered Jul 01 '14 at 13:06

5

C# doesn't have "And" and "Or". It has "&&" and "||".

"AndAlso" and "OrElse" were added to Visual Basic to provide a [new] syntax for "short-circuiting" the evaluation of conditions (which C# has always done, but Basic didn't). There was a lot of "discussion" early on about whether the existing operators should be reworked to support this but, for compatibility with existing code, new operators were added instead.

answered Jul 01 '14 at 13:06

Phill W.

12,181

6

C# does have "And" and "Or", though, in the form of "&" and "|". Typically these are used for bit manipulation, but they perform exactly as expected on Boolean variables. They can be used for non-short-circuiting Boolean logic. – KChaloux Jul 01 '14 at 13:25
I think your answer would be improved by including the information in KChaloux's comment, as the first sentence is incorrect otherwise. – Andrew Morton May 30 '23 at 19:02

score 1 · Answer 2 · answered Jul 01 '14 at 13:09

1

There might be some reasons to evaluate both statements when dealing with sideeffects: if you want both to happen!

The best example I can come up right now is logging: you have two checks (both have to be true) and want to log both checks and their results (as a sideffect in the check) - in this case VB's AND is a good idea.

answered Jul 01 '14 at 13:09

Random Dev

453

2

Only insofar as it's a good idea to save a couple of boolean variables by writing brittle code with non-obvious requirements which could easily be broken by a future developer making changes. Just call the two functions, store the results in variables, then do If Var1 And Var2 – Carson63000 Jul 02 '14 at 04:33
Why should this be more brittle than the way you descripe it? If the other developer does not understand the nuances of VB.net than maybe the problem lies there. The difference between And and AndAlso should be obvious to VB.net developers – Random Dev Jul 02 '14 at 04:36
1

The school of thought that functions should avoid side-effects exists for a reason. If you think there's no risk of future programmer error in putting side effects into code that appears to purely be a boolean check, and relying on nobody accidentally replacing the intended-for-backward-compatibility-with-decade-old-code And with an AndAlso, then I guess we'll have to agree to disagree. – Carson63000 Jul 02 '14 at 04:49
LOL ... maybe you should look me up a bit - my main interests are FP and Haskell/Idris ;) ... I am the last to tell people to sprinkle sideeffects everywhere (indeed I would strongly advise to avoid them anywhere) - but that was not the question - the question was why And is left there at all (or at least that's my interpretation) – Random Dev Jul 02 '14 at 05:00
BTW: where is your take on this? – Random Dev Jul 02 '14 at 05:00

Why And is needed when there is AndAlso

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