分配和逻辑AND

Question

What happens to Y value? I understand "assignment" operator has higher precedence than "and" logical operator. But what happens to (And false).

Thanks

<?php 
$x = true and false;   //$x will be true
$y = (true and false); //$y will be false

echo "x " .$x; 
echo "y" .$y;

I am seeing this.

x 1
y

Answer 1

First line:

($x = true) and false;   //$x will be true

The result of true is obviously true, so true is assigned to $x. The second expression after and is also executed, because true is true, but the result of false (which is false) is never assigned to something.

$y = (true and false);   //$y will be false

In this case, there are parenthesis around the expression says, that the result of whole expression should be assigned to $y. As true is true, the second expression is also evaluted (like in the first one). But the result of the whole expression is false, because the second expression is false.

Example from the docs:

// The constant true is assigned to $h before the "and" operation occurs
// Acts like: (($h = true) and false)
$h = true and false;