Changing the sign of a number in PHP?

Question

I have a few floats:

-4.50 +6.25 -8.00 -1.75 

How can I change all these to negative floats so they become:

-4.50 -6.25 -8.00 -1.75 

Also I need a way to do the reverse

If the float is a negative, make it a positive.

Answer 1

A trivial

$num = $num <= 0 ? $num : -$num ; 

or, the better solution, IMHO:

$num = -1 * abs($num) 

As @VegardLarsen has posted,

the explicit multiplication can be avoided for shortness but I prefer readability over shortness

I suggest to avoid if/else (or equivalent ternary operator) especially if you have to manipulate a number of items (in a loop or using a lambda function), as it will affect performance.

"If the float is a negative, make it a positive."

In order to change the sign of a number you can simply do:

$num = 0 - $num; 

or, multiply it by -1, of course :)