ruby-on-rails,ruby,boolean-expression

Trying to do this part: user.authenticate(params[:session][:password]) without first knowing if the object exists will throw an error. So you need to make sure you have the user object before you try to run .authenticate on it. Does that make sense?

algorithm,encryption,boolean-logic,boolean-expression

NAND is an irriversible operation: a b (a NAND b) 0 0 1 0 1 1 1 0 1 1 1 0 If b is 0 and you know that the result of (a NAND b) is 1, you cannot know whether a is 0 or 1. Hence, your encryption...

I'm not sure where those numbers 0,4,2,5,7 are coming from, a Karnaugh map (assuming that's what you meant) simply specifies the truth output for given inputs. If a term is missing, then it has no effect on the outcome so either of its two possible values will affect the truth...

java,string,validation,io,boolean-expression

I'll sketch out what I think you can easily tackle with some logic and googling. As I commented, you need to find a way to loop through each char in the string you're passing to validSSN(String s), For example: s = '123-45-6789' You want to loop through 1, then 2,...

This was modified in R 3.2.1 as a result of a bug report. As you've pointed out, the previous behavior made little sense: ...

python,python-2.7,boolean,boolean-logic,boolean-expression

obh.val_1 is "gnd" compares the two objects in memory if they are the same object. Python sometimes interns strings in order to reuse them if they are identical. Using "is" to compare strings will not always have predictable results. In another sense, you sort of called id(obh.val_1) == id("gnd") #id...

compiler-construction,compiler-errors,boolean-expression

If you restrict your formulas to Boolean logic over predicate leaves (e.g., you treat the relational comparisons at "ground literals"), you can verify if a formula is a tautology or not by applying Wang's rules of inference, here captured in a algebraic specification where the axioms can be treated as...

php,mongodb,aggregation,boolean-expression

That's not the right syntax. $or and $and take arrays: ((A && B) || (C && D)) ==> { "$or" : [{ "$and" : [A, B] }, { "$and" : [C, D] }] } ...

c#,if-statement,switch-statement,boolean-expression

You should have put the || expressions in parentheses. The & operator (and the && operator, which is what you actually should have used) has higher precedence, so as long as the direction string matched, the whole expression was true. That said, that code is just crazy (no offense intended...

boolean-logic,boolean-expression

Take a look at this: (a + b)(b' + c)(a + c) = (ab' + 0 + ac + bc)(a + c) = (ab' + ab'c +ac + ac + abc + bc) = (ab' + ab'c + ac + abc + bc) = (ab'(1+c) + ac + bc(a +...

boolean-expression,simplification,boolean-algebra

You can first start by distributivity of multiplication over addition: !X + (!Y + !Z)*(Y + Z) = !X + !Y*Y + !Z*Y + !Y*Z + !Z*Z Then, we can use complementation to remove elements of the form !p*p: = !X + 0 + !Z*Y + !Y*Z + 0 And...

Your code becomes: NSLog(@"IS Live environment %@ so use url %@", [IICore isLiveEnvironment], if([IICore isLiveEnvironment]){@"FirstURL" }else{@"SecondURL"}; ); which is why you have the error. Change kII_URL to be: #define kII_URL ((kIsLiveEnvironment) ? @"FirstURL" : @"SecondURL") ...

jquery,boolean-logic,boolean-expression

I modified your code a bit. Now you can have x number of players in the array and they will switch their states just fine. I commented the most important parts so I don't think you will have problem reading the code. If you have just ask :) JSFiddle: http://jsfiddle.net/ycycghwq/2/...

python,boolean-logic,boolean-expression

Quoting Python documentation, The expression x and y first evaluates x; if x is false, its value is returned; otherwise, y is evaluated and the resulting value is returned. The expression x or y first evaluates x; if x is true, its value is returned; otherwise, y is evaluated and...

java,jsp,struts2,ognl,boolean-expression

You can't use a scriptlet variable in Struts tags unless you put this variable to the value stack. But you'd better not use a scriptlet variable, but the variable value. <%boolean bool_val=true;%> real value : <%=bool_val%><br/> expression evaluated value : <s:set var="bool_val"><%=bool_val%></s:set> <s:if test="#bool_val == 'true'"> TRUE </s:if><s:else> FALSE </s:else>...

php,algorithm,boolean-logic,boolean-expression

It's almost scary to say out loud, but you found one of those rare cases where eval is actually a valid solution instead of a problem on its own. Just 'compiling' your input to PHP will make your life a thousand times easier. For example: $code = 'return '; foreach($keys...

java,variable-assignment,assignment-operator,assign,boolean-expression

This is because = has a lower priority than & (which, by the way, is a boolean operator in your snippets and not a bitwise operator; it is the same as && except that it does not short circuit). Therefore your expression reads (with parens): a = (b & a)...

python,operators,boolean-expression

not is a unary operator, not a function, so please don't use the (..) call notation on it. The parentheses are ignored when parsing the expression and not(1) + 1 is the same thing as not 1 + 1. Due to precedence rules Python tries to parse the second expression...

c++,boolean,boolean-expression

The inner expression: (a < 5) || (c < (a + b)) evaluates a < 5 as false (since a is 10) and c < (a + b) as true (since 8 is less than 10+12). Performing a Boolean "or" operation on false and true gives you true. And, given...

!(x AND y) is equal to !x OR !y (and you can pull a NOT out of a boolean x by double negation, for example: x == !!x so x AND !y (your original expression) is equivalent to !(!x OR y) if you remove the negation (!) from the beginning,...

python,python-2.7,logic,boolean-expression

In Python, all objects may be considered "truthy" or "falsy". Python uses this fact to create a sneaky shortcut when evaluating boolean logic. If it encounters a value that would allow the logic to "short-circuit", such as a True at the beginning of an or, or a False at the...

e) The expression is [a + (~a)bc + (~b)c] a + [(~a)b + (~b)]c we can say that [(~a)b + (~b)] <--> [(~a) + (~b)] (Prove it by yourself:-) a + [(~a) + (~b)]c a + (~a)c + (~b)c we can say that [a + (~a)c] <--> [a + c]...

java,mouseevent,boolean-expression

You can do it like this: boolean leftClicked = e.getButton() == MouseEvent.BUTTON1; boolean rightClicked = e.getButton() == MouseEvent.BUTTON2; ...

javascript,boolean,compare,boolean-expression

Because what is really happening is this: (a == a) == c Which is really just: true == "first" See Operator Precedence....

linux,bash,parsing,awk,boolean-expression

I do not exactly got what is your goal, but I created a small bash script to get any boolean expression and write its truth-table. Maybe this helps. It process any braces, AND, OR and NOT expressions. Variable is anything which starts with a letter (on the language you set)....