Do you know a way to organize boolean expressions in a database while allowing infinite nesting of the expressions? Example: a = 1 AND (b = 1 OR b = 2) The expression as a whole shouldn't be stored as varchar to preserve data integrity. ...
I'm looking for a tool to refactor boolean expression. I've got expressions like a1 => (b1 <=> c or d) AND a2 => (b2 <=> c or d) AND a2 => (b2 <=> c or d) The tool should be able to simplify expressions, e.g. extract the sub expression "c or d" in the example above. Is there a free computer algebra system which can do this? Currentl...
EDIT: Found duplicate once I learned the term for this behaviour. Close as duplicate please. Consider this Class* p = NULL; if( p != NULL && p->Method() == OK ){ // stuff } On all compilers I've worked with, this is quite safe. I.e. the first part of the boolean expression will evaluate to false, and the call to Method() will thus...
Assume active is a "boolean field" (tiny int, with 0 or 1) # Find all active users select * from users where active # Find all inactive users select * from users where NOT active In words, can the "NOT" operator be applied directly on the boolean field? ...
I completely forgot about my Haskell project which is due in a couple of hours, any help would be appreciated. The first part is an evaluation function that has the following type signature: evaluate :: Logic Expr -> [(Variable, Bool)] -> Bool This takes a logic expression and a list of assignment pairs as input and returns the value...
I've got three boolean values A, B and C. I need to write an IF statement which will execute if and only if no more than one of these values is True. In other words, here is the truth table: A | B | C | Result ---+---+---+-------- 0 | 0 | 0 | 1 0 | 0 | 1 | 1 0 | 1 | 0 | 1 0 | 1 | 1 | 0 1 | 0 | 0 | 1 1 | 0 | 1 | 0 1 |...
Hey there SO, I was just wondering if there was any way to make my object return false if placed in an if statement. The reason is I'm making a custom exception class. I would like to be able to do something along the lines of class Dog{ public function lookAround() { if(seeDog()) { return bark; ...
Hey Stackfolk, I tried to ask this before, and messed up the question, so I'll try again. Is it possible to make an object return false by default when put in an if statement? What I want: $dog = new DogObject(); if($dog) { return "This is bad;" } else { return "Excellent! $dog was false!" } Is there a way this is possible? ...
Consider the following method in Java: public static boolean expensiveComputation() { for (int i = 0; i < Integer.MAX_VALUE; ++i); return false; } And the following main method: public static void main(String[] args) { boolean b = false; if (expensiveComputation() && b) { } } Logical conjunction (same as &&) is a commutative o...
Hi I want to have an image bound to a boolean and have the source of the image to depend on the boolean value i.e. true source="image1" false source="image2" I was wondering if there is a way to do it inline without need for a converter. ...
echo empty($location); switch($location){ case (empty($location)): expression 1; break; case ($location%10000==0): expression 2; break; case ($location%100==0): expression 3; break; default: expression 4; break; } When I echo empty($location), it prints out 1, why is expression 1 not executed? ...
Suppose I have the following expression String myString = getStringFromSomeExternalSource(); if (myString != null && myString.trim().length() != 0) { ... } Eclipse warns me that myString might be null in the second phrase of the boolean expression. However, I know some that some compilers will exit the boolean expression entirely if t...
I have to write program that prints a truth table of expressions. So, I wrote the following function: bool(true). bool(fail). tableBody(A,B,E) :- bool(A), bool(B) , write(A) , write(' '), write(B), write(' '), write(E),nl, fail. My problem is that E (wich is expression that contains A and B) is not e...
Hi, I'm a programming student trying to better understand pointers, one of the things I learned is that you can set a pointer to NULL. My question is, what's the difference between these two statements? When would each of them return true/false? if (some_ptr == NULL) if (*some_ptr == NULL) Thanks! ...
Program a SCHEME function sat that takes one argument, a CNF formula represented as above. If we had evaluated (define cnf '((a (not b) c) (a (not b) (not d)) (b d))) then evaluating (sat cnf) would return #t, whereas (sat '((a) (not a))) would return (). You should have following two functions to work: (define comp (lambda (lit) ; ...
I've always thought of the if not x is None version to be more clear, but Google's style guide implies (based on this excerpt) that they use if x is not None. Is there any minor performance difference (I'm assuming not), and is there any case where one really doesn't fit (making the other a clear winner for my convention)?* *I'm referri...
Im trying to understand how boolean logic works when I use NOT. To give an example using awk I have a text file containing CORE PORT CORE PORT COREPORT CORE COREPORT And I would like to remove all COREPORT lines. The way I thought I would do it was with (NOT CORE) AND (NOT PORT) eg awk '/!CORE/&&/!PORT/{print}' But when I try it...
I have expressions like this: (cat OR cats OR kitten OR kitty) AND (dog OR dogs) NOT (pigeon OR firefly) Anyone having idea how to make tables to save those? Before I got request for usage of brackets, I limited usage of operators to avoid ambiguous situations. So only ANDs and NOTs or only ORs and saved those in this manner: operat...
Hello, I have a problem that consist in comparing boolean expressions ( OR is +, AND is * ). To be more precise here is an example: I have the following expression: "A+B+C" and I want to compare it with "B+A+C". Comparing it like string is not a solution - it will tell me that the expressions don't match which is of course false. Any i...
Given that it's valid to write a = b = c = 2; It would also be nice, rather than bool allTwo = a == 2 && b == 2 && c == 2; to instead write bool allTwo = a == b == c == 2; But I can't since a == b evaluates to a boolean which can't then be compared to an integer. Is there a language-design reason it has been implemented this w...