logical-operators

Strange question, but someone showed me this, I was wondering can you use the not ! operator for int in C++? (its strange to me). #include <iostream> using namespace std; int main() { int a=5, b=4, c=4, d; d = !( a > b && b <= c) || a > c && !b; cout << d; system ("pause"); return 0; } Yes. For integral types, ! returns true if the operand is zero, and false otherwise. So !b here just means b == 0 . This is a particular case where a value is converted to a bool . The !b can be viewed as !((bool)b) so the question is what is the "truthness" of b . In C++, arithmetic types, pointer types and

This question already has an answer here: Logical Operators, || or OR? 8 answers I've always used || (double pipe) for if (($a == $b) || ($a == $c)) { } and or for do_this() or do_that(); . Why not if (($a == $b) or ($a == $c)) { } or do_this() || do_that(); ? Is there any reason to use any of these two logical operators or it is just a personal preference? The same applies for && vs and , which i only use && . Joni The "spelled out" operators and and or have lower precedence, even lower than assignment, so you may use them to avoid having to write parentheses in so many places. For example:

I thought Java had short circuit evaluation, yet this line is still throwing a null pointer exception: if( (perfectAgent != null) && (perfectAgent.getAddress().equals(entry.getKey())) ) { In this case perfectAgent is null , so I just want the whole expression to return false , but my app is still crashing on this line with a NullPointerException. EDIT, general response: Since perfectAgent is null , nothing to the right of the && should be executed, as it is impossible for the expression to be true. More to the point, it is impossible to execute perfectAgent.getAddress() since perfectAgent does

I have a doubt in the program below. int main() { int i = -3,j = 2, k = 0,m; m = ++i || ++j && ++k; printf("%d %d %d %d\n", i, j, k, m); return 0; } I get the output as -2 2 0 1 . In OR operation if 1st value is true then it won't evaluate the 2nd one so i = -2 and j =2 . Then comes the AND operation . It will check for both the value to be true.So if k = 1 then m = 1 . So the output should be -2 2 1 1 . I run and check and got output as -2 2 0 1 but I could not understand how. You used a short circuit or. Since ++i evaluates to -2, which is not 0, it short circuits and doesn't evaluate the

This question already has an answer here: Is it okay to use “and”, “or” etc. instead of “&&”, “||”? 8 answers Should “not, and, or, not_eq..” be used in c++ 5 answers I saw alternative operators (like and , or , not etc.) when browsing cppreference. They are alternatives to "normal" operators like && , || , ! etc. I examined the assembly for code that uses && and and . Both versions generated the same assembly. Code : #include <iostream> int n = 1; int main() { // if(n > 0 && n < 5) if(n > 0 and n < 5) { std::cout << "n is small and positive\n"; } } So my questions are: What is the difference

In JavaScript (f1() || f2()) won't execute f2 if f1 returns true which is usually a good thing except for when it isn't. Is there a version of || that doesn't short circuit? Something like var or = function(f, g){var a = f(); var b = g(); return a||b;} Nope, JavaScript is not like Java and the only logical operators are the short-circuited https://developer.mozilla.org/en/JavaScript/Reference/Operators/Logical_Operators Maybe this could help you: http://cdmckay.org/blog/2010/09/09/eager-boolean-operators-in-javascript/ | a | b | a && b | a * b | a || b | a + b | |-------|-------|--------|-----

What the different between logical operators and , or and bitwise analogs & , | in usage? Is there any difference in efficiency in various solutions? Logical operators operate on logical values, while bitwise operators operate on integer bits. Stop thinking about performance, and use them for they're meant for. if x and y: # logical operation ... z = z & 0xFF # bitwise operation Logical operators are used for booleans, since true equals 1 and false equals 0. If you use (binary) numbers other than 1 and 0, then any number that's not zero becomes a one. Ex: int x = 5; (101 in binary) int y = 0;