conditional-operator

问题 I have an unexpected issue when using a conditional operator in java. The code is supposed to check if the ArrayList contains a specific string, then it returns true or false. It is not the first time I do this, but for some reason there's something wrong. This is my code so far: public boolean isDone() { ArrayList<String> al = new ArrayList<String>(); //Defining ArrayList al.add(d1.getText()); // Adding the text from JLabels. al.add(d2.getText()); al.add(d3.getText()); al.add(d4.getText());

问题 I get the following: puts true or true and false # >> true whereas I also get: if true or true and false puts "that's true!" else puts "that's false!" end # >> that's false! Why is true or true and false both true and false (like Schrödinger's cat)? 回答1: It has to do with precedence. puts true or true and false actually evaluates as (puts true) or (true and false) [EDIT: Not exactly. See the note from Todd below.] , and if true or true and false evaluates as if (true or (true and false)) .

问题 This question already has answers here : Closed 9 years ago . Possible Duplicate: What does ‘?’ do in C++? What are these kind of statements in c++ called: testNumber > 1 ? true : false; 回答1: ternary statements 回答2: That's the conditional operator. The expression a ? b : c evaluates to b if a is true and c if a is false . In most languages, this is the only example of a ternary operator, an operator that takes three arguments. 回答3: Conditional Expression Conditional Expression <--------------

问题 I have a hard time understanding sizeof 's behaviour when given a ternary expression. #define STRING "a string" int main(int argc, char** argv) { int a = sizeof(argc > 1 ? STRING : ""); int b = sizeof(STRING); int c = sizeof(""); printf("%d\n" "%d\n" "%d\n", a, b, c); return 0; } In this example (tested with gcc 4.4.3 and 4.7.2, compiled with -std=c99 ), b is 9 (8 characters + implicit '\0' ), c is 1 (implicit '\0' ). a, for some reason, is 4 . I would expect a to be either 9 or 1, based on

问题 Please consider the follwing code construction: condition ? code_if_true : condition2 ? code_if_true2 : code_if_false; This doesn't work for PHP whereas it does for JavaScript. Is there a way to get this working for PHP? 回答1: In PHP, the conditional operator is left-associative[PHP.net], compared to virtually all other languages where it is right-associative. That's why you need to use parentheses to control the order of evaluation 1 : condition ? code_if_true : (condition2 ? code_if_true2 :

问题 I was trying to return value true or false depending upon the condition by using a conditional operator but I got an error. Here is my code, bool isEmpty() { int listSize = Node::size(); listSize > 0 ? return (true) : return (false); return false; } And here is the error, error C2107: illegal index, indirection not allowed Now I am stuck here. I don't get the point.Logically I think it should be correct. Please guide me about it . Thanks 回答1: You can only have expressions* as the operands of

问题 This question already has answers here : ternary operator in matlab (8 answers) Closed 5 years ago . Is there a one-liner in MATLAB for this? if a > b foo = 'r'; else foo = 'g'; end 回答1: Not as elegant as a C style ternary operator but you can take advantage of the fact that matlab will automatically cast logicals into doubles in this situation. So you can just multiply your desired result for true ( r in this case) by your condition ( a > b ), and add that to the product of your desired

问题 I need to dynamically choose the width of a <p:panelGrid> based on a backing bean property. However it is not working for me. I have a feeling that I have some syntax error in my code. <p:panelGrid style="width:#{myBean.fromCCRM} ?70%:90%"> ... </p:panelGrid> 回答1: The entire statement needs to go inside #{...} . style="width:#{myBean.fromCCRM ? '70%' : '90%'}" 来源： https://stackoverflow.com/questions/12292397/how-to-use-el-conditional-operator-in-jsf-component-attribute

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . Do you find the following C# code legible? private bool CanExecuteAdd(string parameter) { return this.Script == null ? false :

问题 This question already has answers here : Short form for Java If statement returns NullPointerException when one of the returned objects is null [duplicate] (3 answers) Closed last year . While executing the following code, I am getting a NullPointerException at line: value = condition ? getDouble() : 1.0; In earlier lines when I use null instead of getDouble() everything works and this is strange. public class Test { static Double getDouble() { return null; } public static void main(String[]