short-circuiting Questions

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Is left-to-right evaluation of logical operators (&& ||) guaranteed? Let's say I have this: SDL_Event event; if (SDL_PollEvent(&event)) { if (event.type == SDL_QUIT) { // do ...

7

If I write two SELECT statements in a IF EXISTS condition with a AND clause in between these select queries, does both queries get executed even if the first SELECT returns false? IF EXISTS (SELEC...
March asked 4/4, 2011 at 18:54

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When using the ?? operator in C#, does it short circuit if the value being tested is not null? Example: string test = null; string test2 = test ?? "Default"; string test3 = test2 ?? test.ToLower...
Lytic asked 15/3, 2011 at 22:36

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While performing a check if there's a camera present and enabled on my windows mobile unit I encountered something I don't understand. The code looks like this: public static bool CameraP(){ r...
Thruway asked 8/3, 2011 at 13:31

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When encountering a (bool1 && bool2), does c++ ever attempts to check bool2 if bool1 was found false or does it ignore it the way PHP does? Sorry if it is too basic of a question, bu...
Eolanda asked 6/3, 2011 at 17:5

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Following the usual short-circuit evaluation question, does short-circuit evaluation work for parameters built and sent against nil objects? Example: NSMutableArray *nil_array = nil; .... [nil_arr...
Imperfection asked 13/2, 2011 at 16:37

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I'm new to Haskell, and I'm trying a bit: isPrime :: Integer->Bool isPrime x = ([] == [y | y<-[2..floor (sqrt x)], mod x y == 0]) I have a few questions. Why when I try to load the .hs, ...
Topic asked 27/12, 2010 at 20:1

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For example: def foo(): print 'foo' return 1 if any([f() for f in [foo]*3]): print 'bar' I thought the above code should output: foo bar instead of : foo foo foo bar Why ? how can...
Cheeks asked 29/11, 2010 at 8:18

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I have such code: if(object != null && object.field != null){ object.field = "foo"; } Assume that object is null. Does this code result in nullPointerException or just if statement wo...
Denticle asked 12/11, 2010 at 10:36

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While debugging javascript written by someone else, I came across some code that I've not seen before. Here's a sample: function doSomething() { //doing something here... } function doItNow() { ...

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I've got a query that I've just found in the database that is failing causing a report to fall over. The basic gist of the query: Select * From table Where IsNull(myField, '') <> '' And IsNu...
Evyn asked 21/9, 2010 at 12:43

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If I have the following ... a OrElse b ... and a is True then clearly b is never evaluated. But if I add an Or, then what? a OrElse b Or c Does/should c get evaluated? And what if I put in s...
Hogue asked 9/9, 2010 at 14:45

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I wrote a simple script to solve a "logic puzzle", the type of puzzle from school where you are given a number of rules and then must be able to find the solution for problems like "There are five ...

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Do we have any operator in C# by which I can avoid short circuit evaluation and traverse to all the conditions. say if(txtName.Text.xyz() || txtLastName.Text.xyz()) { } public static bool xyz...
Siler asked 14/7, 2010 at 8:2

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Sorry if this sounds like a really silly question. But I Googled the web and also Googled specifically both the php.net site and the stackoverflow.com site. I know PHP does short circuit lazy eval...
Fulcrum asked 10/7, 2010 at 21:36

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In other words, do the following two statements behave the same way? isFoobared = isFoobared && methodWithSideEffects(); isFoobared &= methodWithSideEffects(); I realize I could just...
Generate asked 30/6, 2010 at 18:25

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I'm trying to find out how I can do an "early return" in a scheme procedure without using a top-level if or cond like construct. (define (win b) (let* ((test (first (first b))) (result (every (l...
Rajkot asked 12/3, 2010 at 16:50

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I tried something along the lines of: if(myString != nil && myString.length) { ... } And got: -[NSNull length]: unrecognized selector sent to instance Does Objective-C not short-circui...
Cyrilla asked 13/1, 2010 at 22:23

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Suppose I want to check a bunch of objects to make sure none is null: if (obj != null && obj.Parameters != null && obj.Parameters.UserSettings != null) { // do something with o...
Faefaeces asked 16/12, 2009 at 20:40

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I thought Java had short circuit evaluation, yet this line is still throwing a null pointer exception: if( (perfectAgent != null) && (perfectAgent.getAddress().equals(entry.getKey())) ) { ...
Paresh asked 29/11, 2009 at 21:4

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I'm new to c++ and am curious how the compiler handles lazy evaluation of booleans. For example, if(A == 1 || B == 2){...} If A does equal 1, is the B==2 part ever evaluated?
Crosscrosslet asked 25/11, 2009 at 18:39

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Given: WHERE (@Id Is NULL OR @Id = Table.Id) If @Id is null: the expression evaluates to true. Does the second part @Id = Table.Id still get considered? or is it sufficient that the expression e...

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Which of these subroutines is not like the other? sub or1 { my ($a,$b) = @_; return $a || $b; } sub or2 { my ($a,$b) = @_; $a || $b; } sub or3 { my ($a,$b) = @_; return $a or $b; } sub or...
Kennedy asked 3/10, 2009 at 1:43

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I have seen something like the following a couple times... and I hate it. Is this basically 'cheating' the language? Or.. would you consider this to be 'ok' because the IsNullOrEmpty is evaluated f...
Raceway asked 7/5, 2009 at 20:47

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I have a couple of methods that return a bool depending on their success, is there anything wrong with calling those methods inside of the IF() ? //&& makes sure that Method2() will only g...
Harrier asked 23/2, 2009 at 21:6

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