Summary: in this tutorial, you will learn how to use the PHP NOT operator (!) to build complex logical expressions.
Introduction to the PHP NOT operator
Unlike the logical AND and OR operators that accept two operands, the logical NOT operator accepts only one operand and negates the operand.
In other words, the logical NOT operator returns true
if the operand is false
and returns false
if the operand is true
.
PHP uses the both not
keyword and (!
) to represent the logical NOT operator.
not expression
Or
! expression
The following table illustrates the result of the logical NOT operator:
Expression | not Expression |
---|---|
true | false |
false | true |
The logical NOT operator is also known as the logical negation operator.
PHP NOT operator examples
The following example illustrates how to use the logical not operator (!
):
<?php
$priority = 5;
var_dump( ! $priority < 5 );
Code language: HTML, XML (xml)
Output:
bool(true)
Code language: JavaScript (javascript)
In this example, PHP evaluate the expression ! $priority < 5
in the following order:
- First,
$priority < 5
evaluates tofalse
. - Second,
! false
evaluates totrue
.
Summary
- PHP NOT operator (
not
,!
) accepts an operand and negate the result of the operand.