That’s just horrible code. It’s badly formatted. I don’t see the hierarchy of the expression. Even if it had good formatting, the expression would be way too complex to quickly parse with the human eye. The intention is unclear. What’s the purpose of those conditions? So what can you do? Use conditional statements (if). Extract … Read more
The performance difference is negligible. The && operator won’t check the right hand expression when the left hand expression evaluates false. However, the & operator will check both regardless, maybe your confusion is caused by this fact. In this particular example, I’d just choose the one using &&, since that’s better readable.
Expressions don’t have return types, they have a type and – as it’s known in the latest C++ standard – a value category. A conditional expression can be an lvalue or an rvalue. This is its value category. (This is somewhat of a simplification, in C++11 we have lvalues, xvalues and prvalues.) In very broad … Read more
It works like this: (condition) ? true-clause : false-clause It’s most commonly used in assignment operations, although it has other uses as well. The ternary operator ? is a way of shortening an if-else clause, and is also called an immediate-if statement in other languages (IIf(condition,true-clause,false-clause) in VB, for example). For example: bool Three = … Read more
Performance The ternary operator shouldn’t differ in performance from a well-written equivalent if/else statement… they may well resolve to the same representation in the Abstract Syntax Tree, undergo the same optimisations etc.. Things you can only do with ? : If you’re initialising a constant or reference, or working out which value to use inside … Read more
This is explained in the Perl documentation. Because of Perl operator precedence the statement is being parsed as ($condition ? $a= 2 : $a ) = 3 ; Because the ?: operator produces an assignable result, 3 is assigned to the result of the condition. When $condition is true this means ($a=2)=3 giving $a=3 When … Read more
The null coalesce operator is much clearer when checking for null, that is its main purpose. It can also be chained. object a = null; object b = null; object c = new object(); object d = a ?? b ?? c; //d == c. While that operator is limited to null checking, the ternary … Read more
UPDATE: This question was the subject of my blog on May 27th 2010. Thanks for the great question! There are a great many very confusing answers here. Let me try to precisely answer your question. Let’s simplify this down: object value = whatever; bool condition = something; decimal result = (decimal)(condition ? value : 0); … Read more
I tested the following page in Tomcat 5.59, JSP 2.0 and JSTL 1.1. It ran without any errors. <%@taglib uri=”http://java.sun.com/jsp/jstl/core” prefix=”c”%> <c:set var=”value” scope=”request” value=”someValue”/> <c:out default=”None” escapeXml=”true” value=”${not empty value ? value : ‘None’}” /> <c:out default=”None” escapeXml=”true” value=”${empty value ? ‘None’ : value}” /> <c:set var=”value” scope=”request” value=”” /> <br/> <c:out default=”None” escapeXml=”true” … Read more
Both i and j are glvalues (see this value category reference for details). Then if you read this conditional operator reference we come to this point: 4) If E2 and E3 are glvalues of the same type and the same value category, then the result has the same type and value category So the result … Read more