logical-operators

问题 I'm looking for a general regex construct to match everything in pattern x EXCEPT matches to pattern y. This is hard to explain both completely and concisely...see Material Nonimplication for a formal definition. For example, match any word character ( \w ) EXCEPT 'p'. Note I'm subtracting a small set (the letter 'p') from a larger set (all word characters). I can't just say [^p] because that doesn't take into account the larger limiting set of only word characters. For this little example,

问题 Iam using searchkick library as an elasticsearch client for Product searching. https://github.com/ankane/searchkick It is possible to create 'OR' condition and 'AND' condition; AND operation Product.search where: {price: {lte: 200}, in_stock: true} OR operation Product.search where: {or: [[{in_stock: true}, {backordered: true}]]} But Iam stuck with creating multiple 'AND' 'OR' conditions with searchkick. I need something like A OR B OR ( C AND D ) or I need like this, A AND B AND ( C OR D )

问题 I came across the following logical operators workaround but could not comprehend the logic behind: console.log(1 && 2) will get you 2 console.log(false && X) will get you false console.log(true && X) will get you UncaughtReferenceError:X is not defined Anyone can explain the answer? 回答1: Look at the documentation for the && operator: && ; Returns expr1 if it can be converted to false; otherwise, returns expr2. Thus, when used with Boolean values, && returns true if both operands are true;

问题 I came across the following logical operators workaround but could not comprehend the logic behind: console.log(1 && 2) will get you 2 console.log(false && X) will get you false console.log(true && X) will get you UncaughtReferenceError:X is not defined Anyone can explain the answer? 回答1: Look at the documentation for the && operator: && ; Returns expr1 if it can be converted to false; otherwise, returns expr2. Thus, when used with Boolean values, && returns true if both operands are true;

问题 Why doesn't func3 get executed in the program below? After func1, func2 doesn't need to get evaluated but for func3, shouldn't it? if (func1() || func2() && func3()) { System.out.println("true"); } else { System.out.println("false"); } } public static boolean func1() { System.out.println("func1"); return true; } public static boolean func2() { System.out.println("func2"); return false; } public static boolean func3() { System.out.println("func3"); return false; } 回答1: You're using a short

问题 I have the following R script: x <- c('PE', 'MG', 'SP', 'GO', 'ES', 'PB', 'DF') y <- c('PB', 'MG', 'SP', 'GO', 'ES', 'SE', 'DF') z <- x == y So that > z [1] FALSE TRUE TRUE TRUE TRUE FALSE TRUE However, I want z (and other logical variables further down the script) to show "Yes" and "No" instead, so I do this recoding: z <- ifelse(z == TRUE, "Yes", "No") Is there any way to skip this extra step, i.e., define z show "Yes" instead of "TRUE" and "No" instead of "FALSE". Of course, I could also

问题 If you have a switch statement and want certain code to be run when the value is one value or another how do you do it? The following code always goes to the default case. #include <iostream> using namespace std; int main() { int x = 5; switch(x) { case 5 || 2: cout << "here I am" << endl; break; default: cout << "no go" << endl; } return 0; } 回答1: Like this: switch (x) { case 5: case 2: cout << "here I am" << endl; break; } Known as "falling through". Just to point out that the reason the

问题 This question already has answers here : Is short-circuiting logical operators mandated? And evaluation order? (7 answers) Closed 2 years ago . I have a question concerning pre and post increments with logical operators if I have this code void main() {int i = - 3 , j = 2 , k = 0 , m ; m=++i||++j&&++k; printf("%d %d %d %d",i,j,k,m);} knowing that the increment and the decrement operators have higher precedence than && and || So they'll be executed first Then the && is higher than means -2||3&

问题 Introduction to problem setup I was doing some benchmarks involving - ~A and A==0 for a double array with no NaNs , both of which convert A to a logical array where all zeros are converted to true values and rest are set as false values. For the benchmarking, I have used three sets of input data – Very small to small sized data - 15:5:100 Small to medium sized data - 50:40:1000 Medium to large sized data - 200:400:3800 The input is created with A = round(rand(N)*20) , where N is the parameter

问题 This question already has answers here : How to test multiple variables against a value? (24 answers) Closed 2 years ago . I'm trying to create a small python program to emulate rolling a single die. My problem arises in that I want the program to accept both upper and lower-case 'Y' to trigger a re-roll. My program works when I accept either upper or lower case y but when I try to change the line if usr == 'Y' to if usr == 'Y' or 'y' creates a problem where it never enters the else statement