How to Convert Positive Numbers to Negative in PHP?

In PHP, you can convert a positive number to negative in the following ways:

• Using Negation Operator;
• Using Arithmetic Operators.

If you wish to always return a negative number (i.e. retain the sign of a negative number whilst ensuring that any positive number is converted to negative), then you can first convert the number to its absolute form, and then negate it.

Using Negation Operator

You can convert a positive number to negative by using the negation operator (-) like so:

-n

For example, you can use this in the following way:

$num = 1234;
$negated = -$num;

var_dump($negated); // -1234

Using Arithmetic Operators

You can convert a positive number to negative by simply multiplying or dividing it by -1:

n * -1

n / -1

Alternatively, you may subtract the number from 0:

0 - n

You can use any of these to convert a positive number to a negative number, for example, like so:

$num = 1234;
$negated = $num * -1;

var_dump($negated); // -1234

$num = 1234;
$negated = $num / -1;

var_dump($negated); // -1234

$num = 1234;
$negated = 0 - $num;

var_dump($negated); // -1234