What is ?: in PHP 5.3? [duplicate]
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');
$c();
?>
Twitto uses several new features available as of PHP 5.3:
- The DIR constant
- The ?: operator
- Anonymous functions
What does number 2 do with the ?: in PHP 5.3?
Also, what do they mean by anonymous functions? Wasn't that something that has existed for a while?
?:
is a form of the conditional operator which was previously available only as:
expr ? val_if_true : val_if_false
In 5.3 it's possible to leave out the middle part, e.g. expr ?: val_if_false
which is equivalent to:
expr ? expr : val_if_false
From the manual:
Since PHP 5.3, it is possible to leave out the middle part of the conditional operator. Expression
expr1 ?: expr3
returnsexpr1
ifexpr1
evaluates toTRUE
, andexpr3
otherwise.
The ?:
operator is the conditional operator (often refered to as the ternary operator):
The expression
(expr1) ? (expr2) : (expr3)
evaluates toexpr2
ifexpr1
evaluates to TRUE, andexpr3
ifexpr1
evaluates to FALSE.
In the case of:
expr1 ?: expr2
The expression evaluates to the value of expr1
if expr1
is true and expr2
otherwise:
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression
expr1 ?: expr3
returnsexpr1
ifexpr1
evaluates to TRUE, andexpr3
otherwise.
Look here:
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.
Anonymous functions: No, they didn't exist before 5.3.0 (see the first note below the examples), at least in this way:
function ($arg) { /* func body */ }
The only way was create_function()
, which is slower, quite cumbersome and error prone (because of using strings for function definitions).