short-circuiting

I am debugging code that has in it expr1 & expr2 where expr1 has a side effect that affects expr2 evaluation result. I suspect that expr2 gets evaluated before expr1 , since JLS guarantees left-to-right evaluation for && , but not necessarily for & . I also suspect that change of evaluation order may be a result of optimization performed by HotSpot (we're running Java 6u20). Do you know if HotSpot can make such an optimization? Better yet, provide any pointers to documentation that either support or eliminate the suspicion. Thanks in advance. EDIT: Thanks for those suggesting to rewrite the

I'm learning the book named Data Structures & Algorithms in Python . On Page 12 that introduce the Logical Operators , it writes: The and and or operators short-circuit , (I thinks it should add is called ), in that they do not evaluate the second operand if the result can be determined based on the value of the first operand. This feature is useful when constructing Boolean expressions in which we first test that a certain condition holds (such as a reference not being None), and then test a condition that could have otherwise generated an error condition had the prior test not succeeded . I

I was reading my textbook for my computer architecture class and I came across this statement. A second important distinction between the logical operators ' && ' and ' || ' versus their bit-level counterparts ' & ' and ' | ' is that the logical operators do not evaluate their second argument if the result of the expression can be determined by evaluating the first argument. Thus, for example, the expression a && 5/a will never cause a division by zero, and the expression p && *p++ will never cause the dereferencing of a null pointer. (Computer Systems: A Programmer's Perspective by Bryant and

In C++17, are fold expressions subject to short-circuiting when used with && or || as their operator? If so, where is this specified? Yes, fold expressions using && or || as the operator can short-circuit, subject to the usual caveat that it happens for the built-in meaning, but not for an overloaded operator function. The meaning of a fold-expression is defined in [temp.variadic]/9: The instantiation of a fold-expression produces: ((E_1 op E_2) op ... ) op E_N for a unary left fold, E_1 op ( ... op (E_N_minus_1 op E_N)) for a unary right fold, (((E op E_1) op E_2) op ... ) op E_N for a binary

I am currently developing a compiler for a very limited object oriented language. I want to treat all values as objects and operators on those values will be implemented as methods. The compiler transforms the program into assembler for a stack-based virtual machine. During compilation I transform integer literals into objects of a special "Integer" class. Arithmetic operators are implemented as methods of that class (using inline assembler). So that 4 + 5 basically equals to 4.add(5) . The problem I am facing right now is the special case for boolean values. If there is an if statement: if(10

What is the difference between the | and || logical operators in MATLAB? I'm sure you've read the documentation for the short-circuiting operators , and for the element-wise operators . One important difference is that element-wise operators can operate on arrays whereas the short-circuiting operators apply only to scalar logical operands. But probably the key difference is the issue of short-circuiting. For the short-circuiting operators, the expression is evaluated from left to right and as soon as the final result can be determined for sure, then remaining terms are not evaluated. For

I need to query data from a second table, but only if a rare set of conditions in the primary table is met: SELECT ..., IF(a AND b AND c AND (SELECT 1 FROM tableb ...)) FROM tablea ... a, b, and c conditions are almost always false, so my thinking is the subquery will never execute for most rows in the result set and thus be way faster than a join. But that would only true if the IF() statement short circuits. Does it? Thanks for any help you guys can provide. The answer is YES. The IF(cond,expr_true,expr_false) within a mysql query is short-circuited. Here a test, using @variables to prove

I'm aware of Swift's higher-order functions like Map, Filter, Reduce and FlatMap, but I'm not aware of any like 'All' or 'Any' which return a boolean that short-circuit on a positive test while enumerating the results. For instance, consider you having a collection of 10,000 objects, each with a property called isFulfilled and you want to see if any in that collection have isFulfilled set to false. In C#, you could use myObjects.Any(obj -> !obj.isFulfilled) and when that condition was hit, it would short-circuit the rest of the enumeration and immediately return true . Is there any such thing