@user1121588 answered most of this in a comment, but to answer fully… “Bitwise and” (&) behaves much the same as logical_and on boolean arrays, but it doesn’t convey the intent as well as using logical_and, and raises the possibility of getting misleading answers in non-trivial cases (packed or sparse arrays, maybe). To use logical_and on … Read more
When i gets to -1, the value of ~i is ~-1, or 0, so the while loop stops executing. The ! operator works because it does something completely different; it results in 1 for 0 values and 0 for all other values. ~ is a bitwise negation. A little more in detail: ~ takes each … Read more
What you’ve written actually almost works (it would work if all the variables were numbers), but it’s not an idiomatic way at all. (…) parentheses indicate a subshell. What’s inside them isn’t an expression like in many other languages. It’s a list of commands (just like outside parentheses). These commands are executed in a separate … Read more
Try this: [model1, model2].map(&:valid?).all? It’ll return true if both are valid, and create the errors on both instances.
Use &&/AND/and, not ||/OR/or: v != “x” && v != “y” && v != “z” Problem If an if block is always executed, the condition for the if block always evaluates to true. The logical expression must be wrong. Let us consider v != “x” || v != “y” || v != “z” for each … 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
In Java, if ( i != 0 ) is the idiomatic way to check whether the integer i differs from zero. If i is used as a flag, it should be of type boolean and not of type int.
sed -e ‘s/add fast \(pkg\|package\) boots-.*/add yinst pkg boots-5.0/g’ You could always avoid the OR by doing it twice sed ‘s/add fast pkg boots-.*/add yinst pkg boots-5.0/g s/add fast package boots-.*/add yinst pkg boots-5.0/g’