Grouping Conditions in PHP

Although the and operation has precedence over or, it is often more convenient to use grouping parentheses to explicitly show the precedence of operations:

<?php
	$num = 3;
	
	if ( ($num > 0 and $num < 5) or ($num > 10 and $num < 20) ) {
		echo '+++';
	} else {
		echo '---';
	}
?>

Of course, grouping can also be used in the case when you need your own priority of operations, and not the one that is obtained by default.

In the code below, specify the priority of operations explicitly:

<?php
	$num = 3;
		
	if ($num > 5 and $num < 10 or $num == 20) {
		echo '+++';
	} else {
		echo '---';
	}
?>

In the code below, specify the priority of operations explicitly:

<?php
	$num = 3;
		
	if ($num > 5 or $num > 0 and $num < 3) {
		echo '+++';
	} else {
		echo '---';
	}
?>

In the code below, specify the priority of operations explicitly:

<?php
	$num = 3;
		
	if ($num == 9 or $num > 10 and $num < 20 or $num > 20 and $num < 30) {
		echo '+++';
	} else {
		echo '---';
	}
?>