conditional-operator

Possible Duplicate: What are the PHP operators “?” and “:” called and what do they do? From http://twitto.org/ <?PHP require __DIR__.'/c.php'; if (!is_callable($c = @$_GET['c'] ?: function() { echo 'Woah!'; })) throw new Exception('Error'); $c(); ?> Twitto uses several new features available as of PHP 5.3: The DIR constant The ?: operator Anonymous functions What does number 2 do with the ?: in PHP 5.3? Also, what do they mean by anonymous functions? Wasn't that something that has existed for a while? Ben James ?: is a form of the conditional operator which was previously available only as:

I saw this today in some PHP code: $items = $items ?: $this->_handle->result('next', $this->_result, $this); I'm not familiar with the ?: operator being used here. It looks like a ternary operator, but the expression to evaluate to if the predicate is true has been omitted. What does it mean? BalusC It evaluates to the left operand if the left operand is truthy , and the right operand otherwise. In pseudocode, foo = bar ?: baz; roughly resolves to foo = bar ? bar : baz; or if (bar) { foo = bar; } else { foo = baz; } with the difference that bar will only be evaluated once. You can also use

I have : #include<stdio.h> int main() { int a=5,b=6; (a>b)?b=a:b=b; // Here is the error return 0; } But if I replace : (a>b)?b=a:b=b; // Error with (a>b)?(b=a):(b=b); // No-Error I understand the lvalue is a value to which something can be assigned and how is it different from rvalue , but why is the extra parenthesis making the difference. Assignment has a lower precedence than the ternary operator so the line evaluates like: ((a>b)?b=a:b)=b; use: b=(a>b)?a:b; Nawaz Actually, in C, this code (a>b)?b=a:b=b; is parsed by many compilers as ((a>b)?b=a:b)=b; which is an error, as the expression (

I'd like to go from this: if($var == 3 || $var == 4 || $var == 5 || $var =='string' || $var == '2010-05-16') { // execute code here } to this: if($var == (3, 4, 5, 'string', '2010-05-16')) { // execute code here } Seems very redundant to keep typing $var , and I find that it makes it a bit cumbersome to read. Is there a way in PHP to do simplify it in this way? I read on a post here that when using XQuery you can use the = operator as in $var = (1,2,3,4,5) etc. Place the values in an array, then use the function in_array() to check if they exist. $checkVars = array(3, 4, 5, "string", "2010-05

I was writing a console application that would try to "guess" a number by trial and error, it worked fine and all but it left me wondering about a certain part that I wrote absentmindedly, The code is: #include <stdio.h> #include <stdlib.h> int main() { int x,i,a,cc; for(;;){ scanf("%d",&x); a=50; i=100/a; for(cc=0;;cc++) { if(x<a) { printf("%d was too big\n",a); a=a-((100/(i<<=1))?:1); } else if (x>a) { printf("%d was too small\n",a); a=a+((100/(i<<=1))?:1); } else { printf("%d was the right number\n-----------------%d---------------------\n",a,cc); break; } } } return 0; } More specifically