Firstly is there a name for this expression ?
Javascript
var value = false || 0 || '' || !1 || 'string' || 'wont get this far';
value equals string (string) aka the fifth option
PHP
$value = false || 0 || '' || !1 || 'string' || 'wont get this far';
$value equals true (bool)
Am I right in thinking the correct way to achieve the same result as JavaScript is by nesting ternary operators? What is the best solution ?
The equivalent operator in PHP is ?:, which is the ternary operator without the middle part:
$value = false ?: 0 ?: '' ?: !1 ?: 'string' ?: 'wont get this far';
$a ?: $b is shorthand for $a ? $a : $b.
|| returns one of its operands, not a boolean. The equivalent way to do that in PHP is ?:. Question answered.
If You are using PHP 5.3 or higher see deceze's answer.
Other wise you could use nested regular ternary operators.
$value = ( false ? false : ( 0 ? 0 : ( '' ? '' : ( !1 ? !1 : ( 'string' ? 'string' : ( 'wont get this far' ? 'wont get this far' : null ))))));
Wow thats ugly.
You could use an array of values instead;
$array = array(false,0,'',!1,'string','wont get this far'));
Now create a function which iterates over the array and returns the first true value.
function array_short_circuit_eval($vars = array()){
foreach ($vars as $var)if($var)return $var;return null;
}
$value = array_short_circuit_eval($array);
echo $value; // string
$value = current(array_filter(array(false, 0, ...))) – I hope nobody needs to use this, but here it is...This test false || 0 || '' || !1 || true || 'wont get this far' will return a boolean value. It will return true if any of the values is true, that's how the OR works. It's not a ternary expression, which applies the first valid value to the receiving variable.
It returns 1 to PHP because you didn't cast the expression as a boolean.
You could do this to make the expression return a boolean value instead of an integer into your PHP variable:
$value = (bool)(false || 0 || '' || !1 || true || 'wont get this far');`
The return will be true.
.. || .. will return a boolean value...", "You could do this to make the expression return a boolean value..." – Which is it? Does || return a boolean or doesn't it?
|| won't get any more boolean by casting it.Another approche with 'or' and '=' operators.
example:
in Javascript:
$value = false || 0 || !1 || 'woow, i am selected';
in Php:
$value = false or $value = 0 or $value = !1 or $value = 'woow, i am selected';
This is possible because in Php 'or' operator has lower precedence order then '=' (assignment).
trueonly..Testecho true;<?php $value = false || 0 || '' || true || 'wont get this far'; echo $value===true?'true':$value; ?>