logical-operators

问题 When I am down to squeezing the last bit of performance out of a kernel, I usually find that replacing the logical operators ( && and || ) with bitwise operators ( & and | ) makes the kernel a little bit faster. This was observed by looking at the kernel time summary in CUDA Visual Profiler. So, why are bitwise operators faster than logical operators in CUDA? I must admit that they are not always faster, but a lot of times they are. I wonder what magic can give this speedup. Disclaimer: I am

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 4 years ago . Is there any meaningful difference between condition && console.log("this may run"); and if (condition) console.log("this may run); If not, which is a best practice? 回答1: You should use the second. Your code should say what it means. That is what is meant by writing "semantic

问题 I have implemented a set datatype in javascript based in a generic object type, like this: function createSetFromList(list) { var set = { }; for (var i = 0; i < list.length; i++) set[list[i]] = true; return set; } Now I can easily check whether a given value belongs to the set: var users = createSetFromList(my_users); if (user in users) allow_operation = true; The problem that I have is that I would like to check if my set is empty, like this: if ("users is empty" or user in users) allow

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 6 years ago . I use this methode in order to check if a link is valid but when I use a logical OR it doesn't work but it works when i use a logical AND it's weird. What do you think? public String verification() { String lien = URL.getText().toString(); if(titre.getText().toString().isEmpty()) { return

问题 My code: import org.ujmp.core.Matrix; import org.ujmp.core.SparseMatrix; public class part { public static void main(String args[]) throws Exception{ Matrix Bigomega=Matrix.Factory.zeros(6,6); Matrix omega = SparseMatrix.Factory.zeros(6, 6); int []timea={1,2,3,4,5,6}; int [] timeb={3}; int k1=0,k2=0; while (k1 < timea.length && k2 < timeb.length ) { if (timea[k1] < timeb[k2]) { omega.setAsInt(1, k1, k1); omega.setAsInt(-1, k1, k1 + 1); omega.setAsInt(-1, k1 + 1, k1); omega.setAsInt(1, k1 + 1,

问题 I'm dealing with if in R and I'm struggling with one of the typical examples: checking if it is a vowel= TRUE and FALSE otherwise. if.function <- function(char){ if (char=('a') or ('e') or ('i') or ('o') or ('u') ) { return(TRUE) } else if (char == 0){ return(FALSE) } Could someone give me a hand? I saw other examples with Python and Java, but I barely know how to use just R. 回答1: char=('a') or ('e') or ('i') or ('o') or ('u') is illegal. Try isVowel <- function(char) char %in% c('a', 'e', 'i

问题 return (empty($neededRole) || strcasecmp($role, 'admin') == 0 || strcasecmp($role, $neededRole) == 0); What exactly does the || mean in this statement? Can someone put this in english for me. I promise I've googled this but I guess I don't know what to google for because I can't find anything. thanks:) 回答1: It is the OR logicial operator. http://www.php.net/manual/en/language.operators.logical.php 回答2: Googling symbols is always hard. Don't worry: || means or in the statement. Don't confuse

问题 Can any one explain why c still equal 15 after execution int main(void) { int t,a=5,b=10,c=15; t= ++a||++c; printf("%d %d %d",t,a,c); } 回答1: The logical-or operator || is a short-circuit operator. If the left side evaluates to a true boolean value (i.e. not 0), then the right side doesn't execute. Similarly for the logical-and operator && , if the left hand side is false (i.e. 0) the right hand side does not execute. 来源： https://stackoverflow.com/questions/31415375/logical-operation-pre

问题 I am trying to write a simple program in Haskell. It should basically run two shell commands in parallel. Here is the code: import System.Cmd import System.Exit import Control.Monad exitCodeToBool ExitSuccess = True exitCodeToBool (ExitFailure _) = False run :: String -> IO Bool run = (fmap exitCodeToBool) . system main = liftM2 (&&) (run "foo") (run "bar") But command "foo" returns ExitFailure and I expect "bar" never to run. This is not the case! They both run and both show errors on the

问题 I've always been under the impression that for any comparison statement, i.e. X == Y or X != Y is the format, and you chain statements together with && or || . Is there not some way to write X == (Y || Z) instead of X == Y || X == Z ? Edit : Since it has been established that this is not possible to do cleanly, how else could it be done? 回答1: #include <algorithm> #include <array> #include <string> #include <iostream> #include <initializer_list> template<class Type, class Next> bool is_one_of