For your q || a to evaluate to a, q should be a ‘falsy’ value. What you did is called “Short circuit evaluation”. Answering your questions: The logical operators (like and – &&, or – ||) can be used in other situations too. More generally in conditional statements like if. More here Empty string is … Read more
It seems you can’t do it “directly” Try use helper, why not? Register helper in your javascript code: Handlebars.registerHelper(‘ifEquals’, function(arg1, arg2, options) { return (arg1 == arg2) ? options.fn(this) : options.inverse(this); }); Use in template: {{#ifEquals sampleString “This is a string”}} Your HTML here {{/ifEquals}} More details here: Logical operator in a handlebars.js {{#if}} conditional … Read more
Yes, it’s guaranteed, otherwise such operators would lose much of their usefulness. Important notice: this is valid only for the builtin && and ||; if some criminal overloads them, they are treated as “regular” overloaded binary operators, so in this case both operands are always evaluated, and in unspecified order as usual. For this reason, … Read more
The single ampersand & is the logical AND operator. The double ampersand && is again a logical AND operator that employs short-circuiting behaviour. Short-circuiting just means the second operand (right hand side) is evaluated only when the result is not fully determined by the first operand (left hand side) A & B (A and B … Read more
You don’t need to wrap anything in a function – the following works a = c(T,F,NA) a %in% TRUE [1] TRUE FALSE FALSE
You should avoid coding such unreadable code. It is actually parsed as m = (++i && ++j) || ++k; So once j >= 0 the ++j condition is always true, so ++k is not evaluated since && is a short-cutting and then but || is a short-cutting or else (so they may not evaluate their … Read more
You’ll need to split them up using a comma: body[class*=”page-node-add-“], body[class~=”page-node-edit”] {background:red;} The problem with using a comma: … is that you can’t do it any other way than with a comma. Perhaps it could have been remedied with Selectors 3, but unfortunately the spec says otherwise. That is only going to be remedied by … Read more
Store each boolean matrix as an item in a list: result <- vector(“list”,49) for (i in 1:49) { result[[i]] <- T1>F[i] # I used print to see the results in the screen } #Print the first matrix on screen result[[1]]
JavaScript traces its ancestry back to C, and C does not have a logical XOR operator. Mainly because it’s not useful. Bitwise XOR is extremely useful, but in all my years of programming I have never needed a logical XOR. If you have two boolean variables you can mimic XOR with: if (a != b) … Read more
My guess is that’s a direct carry-over from Perl. The operators or and and were added later in Perl 5 for specific situations were lower precedence was desired. For example, in Perl, here we wish that || had lower precedence, so that we could write: try to perform big long hairy complicated action || die … Read more