logical-operators

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

问题 I am trying to combine 2 different logical statements in a single while loop, but having trouble getting the logic correct so that 2 different checks can be evaluated in the same loop. For example, I have the following 2 logical statements. Logic 1 Determine if the entered username is blank and if it is ask the user to re-enter a different username. echo -ne "User Name [uid]$blue:$reset " read USERNAME USERNAME=$(echo "$USERNAME" | tr "[:upper:]" "[:lower:]") while [[ -z "$USERNAME" ]]; do

问题 I'm relatively new to Javascript and programming in general. Today while writing a simple triple dice roll simulator I struck a problem that I worked around but which I still don't understand. Here's my code... // ROLLING TRIPLES var diceSides = 6; var diceOne = Math.floor(Math.random() * diceSides + 1); var diceTwo = Math.floor(Math.random() * diceSides + 1); var diceThree = Math.floor(Math.random() * diceSides + 1); var rolls = 3; while ((diceOne !== diceTwo) || (diceTwo !== diceThree)) {

问题 Why this Java code doesn't work ? How can add logical comparison like || or $$ to type char in the if statement : System.out.println("Type Text"); txt = ms.next(); size = txt.length(); for (int i = 0; i < size; i++) { if ((txt.charAt(i)) == ('a'||'b')) { System.out.println("is the letter A or B"); } } 回答1: You cannot specify the || operator between two char s to mean this character or this other one as you try here : if ((txt.charAt(i)) == ('a'||'b')) { ...} || is a logic OR that has to be

问题 What is the difference between these various uses of the "&&" logical operator? From Oliver Steele's Functional.js library. Line 4, "args.length && arg": 0 Function.prototype.partial = function(){ 1 var fn = this, args = Array.prototype.slice.call(arguments); 2 return function(){ 3 var arg = 0; 4 for ( var i = 0; i < args.length && arg < arguments.length; i++ ) 5 if ( args[i] === undefined ) 6 args[i] = arguments[arg++]; 7 return fn.apply(this, args); 8 }; 9 }; From bootstrap.js. Line 11

问题 I'm pretty sure its probably ( or ) that is causing it maybe one too many of them. $filechk1 = "/temp/files/" . $data[0] . ".doc"; $filechk2 = "/temp/files/" . $data[1] . ".doc"; $dirchk1 = "/temp/files/" . $batchid . "/" .$data[0] . ".doc"; $dirchk2 = "/temp/files/" . $batchid . "/" . $data[1] . ".doc"; if(is_file($filechk1) && (is_file($filechk2))) || (is_file($dirchk1) && (is_file($dirchk2))){ ... } 回答1: Incorrectly placed parentheses. Needs to be this. if ((is_file($filechk1) && is_file(

问题 I basically want to use the function ismember , but for a range. For example, I want to know what data points in array1 are within n distance to array2 , for each element in array2 . I have the following: array1 = [1,2,3,4,5] array2 = [2,2,3,10,20,40,50] I want to know what values in array2 are <= 2 away from array1 : indices(1,:) (where array1(1) = 1) = [1 1 1 0 0 0 0] indices(2,:) (where array1(2) = 2) = [1 1 1 0 0 0 0] indices(3,:) (where array1(3) = 3) = [1 1 1 0 0 0 0] indices(4,:)

问题 This is probably a silly question, but curiosity has gotten the better of me. I've been seeing code lately that seems to "reverse" the order of expressions for relational operators e.g.: if (0 == someVariable) As opposed to what I normally see/write: if (someVariable == 0) To me, the second method seems more readable and intuitive, so I'm wondering if there's some reason I'm seeing the first method? Logically, both statements evaluate to the same result, so is it just a matter of personal

问题 I'm trying an SQLi attack. The compiler executes the following query despite warnings: select * from users where username='A' or 'B' and password='C'; Because the query executes, the attack is successful. Why does this query works and what is it doing? Can I assume that the value 'B' is taken as 'True' in the boolean sense? How do the logical operators work with each other? Is there any specific order like BODMAS for mathematics? Note that 'B' is standalone and not a boolean condition. A

问题 I wrote a leading-NA count function, it works on vectors. However: a) Can you simplify my version? b) Can you also generalize it to work directly on matrix, dataframe (must still work on individual vector), so I don't need apply() ? Try to avoid all *apply functions, fully vectorize, it must still work on a vector, and no special-casing if at all possible. leading_NA_count <- function(x) { max(cumsum((1:length(x)) == cumsum(is.na(x)))) } # v0.1: works but seems clunky, slow and unlikely to be