From the C++ standard: The order of evaluation of arguments is unspecified. All side effects of argument expression evaluations take effect before the function is entered. The order of evaluation of the postfix expression and the argument expression list is unspecified. However, your example would only have undefined behavior if the arguments were x>>=2 and … Read more
Remember that your code is equivalent to: while (std::cin.operator>>(value)) { } Or: while (1) { std::cin >> value ; if (!std::cin) break ; } The “code” always tries to read from std::cin into value before testing std::cin. Let’s look at the quote: […] The input operator (ยง 1.2, p. 8) returns its left operand, which … Read more
First, precedence isn’t an issue here, because foo = bar || (*zap) works no better. The general rule of thumb is that you cannot perform additional operations on a splat. Even something as simple as foo = (*zap) is invalid. This applies to 1.9 as well. Having said that, what do you expect foo = … Read more
Operator precedence 2.x, 3.x. The precedence of not is lower than that of in. So it is equivalent to: >>> not ((True) in [False, True]) False This is what you want: >>> (not True) in [False, True] True As @Ben points out: It’s recommended to never write not(True), prefer not True. The former makes it … Read more
As I mentioned in a comment, this test case can be reduced to: x = {} x[1] = len(x) The question then becomes, is x[1] == 0, or is x[1] == 1? Let’s look at the relevant 2.x documentation and 3.x documentation: Python evaluates expressions from left to right. Notice that while evaluating an assignment, … Read more
Yes, the || operator has higher precedence than the conditional ?: operator. This means that it is executed first. From the page you link: Operator precedence determines the order in which operators are evaluated. Operators with higher precedence are evaluated first. Let’s have a look at all the operations here: step = step || (start … Read more
Any operator has precedence over the method call. It is highly recommended to use () for method calls to avoid situations like the one you’re asking about.
It’s all about Operator Precedence. The Overloaded Bitwise Left Shift Operator operator<<(std::basic_ostream) has a higher priority than the Logical AND Operator &&. #include <iostream> int main() { std::cout << (1 && 0); return 0; } If you are not 146% sure about the priority of an operator, do not hesitate to use brackets. Most modern … Read more
It is not safe to rely on this behavior. I wrote a test script which schedules a number of functions (and they in turn also schedule a number of functions) all using setTimeout(…, 0), and the order in which the functions were called was not always the same as the order in which setTimeout was … Read more
Firstly, application (whitespace) is the highest precedence “operator”. Secondly, in Haskell, there’s really no distinction between operators and functions, other than that operators are infix by default, while functions aren’t. You can convert functions to infix with backticks 2 `f` x and convert operators to prefix with parens: (+) 2 3 So, your question is … Read more