logical-operators

问题 In C++, a bool is guaranteed to be 0 or 1 C++ (§4.5/4): An rvalue of type bool can be converted to an rvalue of type int, with false becoming zero and true becoming one. Consider the following function and what g++5.2 generates with -O3 int foo(bool a, bool b) { if(a&b) return 3; else return 5; } 0000000000000000 <_Z3foobb>: 0: 40 84 ff test %dil,%dil 3: 74 13 je 18 <_Z3foobb+0x18> 5: 40 84 f6 test %sil,%sil 8: b8 03 00 00 00 mov $0x3,%eax d: 74 09 je 18 <_Z3foobb+0x18> f: f3 c3 repz retq 11:

问题 My task is to write a function interpret that takes two arguments, a valid expression and an interpretation, and gives the truth value if the entire expression is true in this particular interpretation. The logical constants and expressions should be managed as strings, so you need to implement their own functions for the Boolean operations. Note that the function should return "true" or "false" not True or False. Here are some possible inputs and outputs: >>> interpret(["door_open", "AND",

问题 so if I have x = 0x01 and y = 0xff and I do x & y , I would get 0x01 . If I do x && y do I still get 0x01 , but the computer just says its true if its anything than 0x00 ? My question is are the bits the same after the operation regardless of bit-wise or logical AND/OR, but the computer just interprets the final result differently? In other words are the hex values of the result of & and && (likewise | and ||) operations the same? edit: talking about C here 回答1: The answer depends on the

问题 SELECT item_name from items WHERE item_id = $var; I tried: $var = 001 || 002 || 003 || 004; $var = 001 OR 002 OR 003 OR 004; $var = 001 or 002 or 003 or 004; But all do not work. Thanks, i try that, but the output only 1 result => 1. What I want is to output all, i.e. 1, 2 , 3 and 4.. Means, I want to select multiple records(rows) from 1 column How to do that? 回答1: SELECT item_name from items WHERE item_id IN (1, 2, 3, 4) And if item_id is a VARCHAR for some reason: SELECT item_name from

问题 Code: #include<stdio.h> int main() { int j = 7, i = 4; j = j || ++i && printf("you can"); printf("%d %d",i,j); return 0; } Output: 4 1 [Code Link][1] The precedence of prefix operator is higher than logical operators. 2.Logical && has higher precedence than logical || . In Logical AND( && ) if first operand evaluates to false than second will not be evaluated and In Logical OR( ||) if first operand evaluates to true , then second will not be evaluated. The complete expression is evaluating to

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 years ago . For instance (Lets say we are talking about C++ if that makes a differnce), In an && operator if I know that one statement will result to 0 more often/has a higher chance then the other statement should I put that on the left side, and the other statement on the right? Same

问题 I would like to run the following query in golang using mgo in a pipeline. {"key1" : 1, "$or" : [{"key2" : 2}, {"key3" : 2}]} I have looked everywhere, but I cannot find an example like this. I have tried many different combinations, for example: ... pipeline := []bson.M{ bson.M{ "$match" : bson.M{ "key1" : 1, "$or" : bson.M{ "key2" : 2, "key3" : 2}, } ... } which compiles correctly, does not find anything. Any ideas? Thank you in advance 回答1: Your mongo query can be translated to the

问题 So, I was writing some code and I was getting an unexpected output in one part of my program which disrupted the entire system. I managed to extract and simplify the problem to a basic logical expression. Let's say: int i = 1, j = 1, k = 0; printf("%d\n", ++i || ++j && k); printf("%d, %d, %d\n", i, j, k); return 0; The output for this program is: 1 2 1 0 I am thinking that the value of j was not incremented to 2 due to the short circuit nature of the || operator. However I am confused how the

问题 In my project there is a Logic evaluation section, it take input as a string which contains logical expressions ( true/false ) . I want to evaluate this string and return a final Boolean value. string Logic="1&0|1&(0&1)" //string Logic="true AND false OR true AND (false AND true)" This will be my Logic . The length might increase. Is there any way to Evaluate this expression from LINQ / Dynamic LINQ ? 回答1: a way without any third party libraries is to use a DataTable with expression. There

问题 This question already has answers here : Is it okay to use “and”, “or” etc. instead of “&&”, “||”? (8 answers) Are “not, and, or, not_eq..” part of the C++ standard? (And why might they be used or avoided in code?) (5 answers) Closed 2 years ago . 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.