PHP - Operator Operator precedence
Introduction
The following table shows the order of precedence of the operators that we've studied until now:
| Operator ** | Type Arithmetic |
|---|---|
| ++, -- | Increasing/decreasing |
| ! | Logical |
| *, /, % | Arithmetic |
| +, - | Arithmetic |
| <, <=, >, >= | Comparison |
| ==, !=, ===, !== | Comparison |
| && | Logical |
| || | Logical |
| =, +=, -=, *=, /=, %=, **= | Assignment |
The expression 3+2*3 will first evaluate the product 2*3 and then the sum, so the result is 9 rather than 15.
To perform operations in a specific order, different from the natural order of precedence, force it by enclosing the operation within parentheses.
Hence, (3+2)*3 will first perform the sum and then the product, giving the result 15 this time.
Demo
<?php
$a = 1; /*from w w w. j a v a 2 s . c o m*/
$b = 3;
$c = true;
$d = false;
$e = $a + $b > 5 || $c; // true
var_dump($e);
$f = $e == true && !$d; // true
var_dump($f);
$g = ($a + $b) * 2 + 3 * 4; // 20
var_dump($g);
?>
Result
