conditional-operator

Possible Duplicate: What does ‘?’ do in C++? What are these kind of statements in c++ called: testNumber > 1 ? true : false; ternary statements 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. Conditional Expression Conditional Expression <------------------------> (x < y) ? x : y |_____| |________| Test Conditional Expression Operator The '?' and ':' make up the conditional operator. Ternary operator. http://en.wikipedia.org

Ternary operator is very useful, why it does not work in this particular case: c="d" d={} d[c]+=1 if c in d else d[c]=1 It gives: d[c]+=1 if c in d else d[c]=1 ^ SyntaxError: invalid syntax I don't see nothing wrong here since the same thing without the ternary operator works: c="d" d={} if c in d: d[c]+=1 else: d[c]=1 The ternary operator works on expressions, not statements. Assignment is a statement. Use a regular if / else . The correct way to write this would be: d[c] = (d[c] + 1) if c in d else 1 来源： https://stackoverflow.com/questions/21277896/python-ternary-operator-and-assignment-in

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? 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 : code_if_false ); 1 The order in which which operators are resolved, not when operands are evaluated. The

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 Kerrek SB You can only have expressions* as the operands of the ternary conditional, not statements. The usual way to say this is: return listSize > 0 ? true

I've done my programming exam in C yesterday. There was a question I could not answer, and even though I've studied today I can't come up with a solution. So we have this: int A= -1 , B= -2, C= -3, X=1; X = B != C ? A=(~C) - A-- : ++C + (~A); printf("A= %d B= %d C =%d X=%d \n", A,B,C,X); I know this operator functions if X = B != C is true then A=(~C) - A-- is executed. If it's false, ++C + (~A) is executed. Can anyone tell me and explain what are the values of A, B, C and X in that printf ? NEW This was included in a question that asks to do a "trace" to the whole program: #include <stdio.h>

How come the conditional operator ( ?: ) doesn't work when used with two types that inherit from a single base type? The example I have is: ActionResult foo = (someCondition)? RedirectToAction("Foo","Bar") : Redirect(someUrl); Where the long form works fine: ActionResult foo; if(someCondition) { foo = RedirectToAction("Foo","Bar"); } else { foo = Redirect(someUrl); } Both return types, RedirectToRouteResult and RedirectResult , inherit from ActionResult . How come the conditional operator (?:) doesn't work when used with two types that inherit from a single base type? The type of the