Logical Operators

Logical Operators return boolean result which makes them suitable for if statements.

Operator	Description	Examples	Result
!	Not - inverse the value.	!true	false
		!false	true
		!(2 + 3 == 5)	false
&&	And true if all statements are true. false - if one or more statements are false.	true && true && true	true
		false && false && false	false
		true && false	false
||	Or true if one or more statements are true. false - if all statements are false.	true || true || true	true
		false || false || false	false
		true || false	true

Example

Let's look at the following example. Depending on a test score, determine whether the score is low, medium, high or invalid following these rules:

• 0 to 50 - low
• 51 to 75 - medium
• 76 to 100 - high
• less than 0 or more than 100 - invalid

<?php $score = 80; if ($score >= 0 && $score <= 50) { echo "low"; } if ($score >= 51 && $score <= 75) { echo "medium"; } if ($score >= 76 && $score <= 100) { echo "high"; } if ($score < 0 || $score > 100) { echo "invalid"; }

Output:

high

Explanation:

• To check whether a number is between 2 values && (AND) operator can be used.
• Line 4 checks whether number is greater or equal to 0 and if it's less or equal to 50.
• Line 16 checks whether number is less than 0 or if it's greater than 100.